IEC 60529, Degrees of protection provided by enclosures IP Code IEC 60730-1, Automatic electrical controls for household and similar use – Part 1: General requirements IEC 60730-2-5, A
General safety strategy
The manufacturer shall ensure that
– all foreseeable hazards, hazardous situations and events associated with the fuel cell power systems throughout their anticipated lifetime have been identified;
– the risk for each of these hazards has been estimated from the combination of probability of occurrence of the hazard and of its foreseeable severity according to ISO 14121,
IEC 61882, IEC 60300-3-9, or IEC 61511-3 as applicable, or equivalent;
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The estimated risks are influenced by two key factors: probability and severity During the design phase, efforts have been made to eliminate or minimize these risks, including considerations for reasonably foreseeable misuse, resulting in an inherently safe design and construction.
– the necessary protection measures in relation to risks that are not or cannot be eliminated have been taken (provision of warning and safety devices);
– users are informed of any additional safety measures that they may be required to implement
To ensure safety in fuel cell systems, it is essential to address potential hazards associated with the stored energy, including fuel, flammable materials, pressurized media, electrical energy, and mechanical energy A comprehensive safety strategy should be developed following a systematic approach.
– eliminate hazards to outside the fuel cell system, when such energy is released nearly instantaneously; or
– passively control (for example, burst disks, release valves, thermal cut-off devices) such forms of energy to ensure a release without endangering the ambient; or
To effectively manage energy forms, electronic control equipment within the fuel cell system must implement appropriate countermeasures based on sensor signal evaluations It is essential to thoroughly investigate any residual risks associated with potential failures in this control equipment For safety-critical components, refer to IEC 61508 for comprehensive guidance.
– provide appropriate safety markings, concerning the remaining risks of hazards
Using the techniques described above, special care shall be taken to address the hazards listed in Annex A
The manufacturer must conduct a safety and reliability analysis to identify potential failures that could significantly impact system safety, ensuring that necessary protective measures are implemented for any remaining risks.
The reliability analysis shall be performed in accordance with IEC 60812, IEC 61025, or equivalent
4.1.3 Behaviour at normal and abnormal operating conditions
The fuel cell system must be designed to endure all standard operating conditions specified by the manufacturer without sustaining damage Additionally, it should be constructed with foresight to handle any anticipated abnormal operating conditions, as outlined in section 4.1.
Physical environment and operating conditions
The design and construction of the fuel cell power system and its protective systems must ensure their effective operation under the specified physical environment and operating conditions outlined in sections 4.2.2 to 4.2.8.
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The fuel cell power system shall be designed to operate correctly with the conditions of electrical power input specified in IEC 60204-1 or as otherwise specified by the manufacturer
The manufacturer shall specify the physical environment conditions for which the fuel cell power system is suitable Consideration should be given to
– the altitude above sea-level up to which the fuel cell power system shall be capable of operating correctly;
– the range of air temperatures and humidity within which the fuel cell power system shall be capable of operating correctly;
– the seismic zone where it may be sited
The fuel cell power system must be engineered to function effectively within the specified composition limits and supply characteristics of its intended fuels, such as pipeline natural gas The manufacturer's user manual should clearly outline these composition limits and supply characteristics for optimal operation of the fuel cell power system.
The quality and supply characteristics of the water to be used in the fuel cell power systems shall be specified by the manufacturer
To mitigate the negative impacts of vibration, shock, and bumps from machinery and the surrounding environment, it is essential to choose appropriate equipment, position it away from the fuel cell power system, or utilize anti-vibration mountings Seismic shock effects are not covered in this context and should be addressed separately if deemed necessary by the manufacturer.
The fuel cell power system must be engineered to endure transportation and storage temperatures ranging from -25 °C to +55 °C, with the capability to handle short durations of up to 24 hours at temperatures as high as +70 °C Manufacturers may specify alternative temperature ranges as needed.
The fuel cell power system or each component part thereof shall
– be capable of being handled and transported safely, when necessary, be provided with suitable means for handling by cranes or similar equipment;
– be packaged or designed so that it can be stored safely and without damage (for example, adequate stability, special supports, etc.)
The manufacturer shall specify special means for handling, transportation and storage if required
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Fuel cell systems must include provisions for purging to ensure a passive state for safety after shutdown or before startup, as directed by the manufacturer A suitable purge system should utilize a medium specified by the manufacturer, which may include nitrogen, air, or steam, provided that the situation is non-hazardous within the intended application.
Selection of materials
All materials shall be suitable for the intended purpose
Manufacturers must take necessary precautions and provide essential information to mitigate risks associated with hazardous materials used in fuel cell power systems, ensuring the safety and health of individuals.
4.3.2 Asbestos or asbestos-containing material(s) shall not be used in the construction of a fuel cell power system
Metallic and non-metallic materials used in the construction of fuel cell power systems, especially those exposed to moisture or containing process gas or liquid streams, must be suitable for all anticipated physical, chemical, and thermal conditions throughout the equipment's expected lifespan This includes all components and materials used for sealing or interconnecting parts, such as welding consumables, ensuring they meet the necessary standards for various test conditions.
The materials must maintain their mechanical stability, including strength, fatigue properties, endurance limit, and creep strength, throughout the entire range of service conditions and lifespan as defined by the manufacturer.
Materials used in equipment must be highly resistant to both chemical and physical actions of the contained fluids, as well as to environmental degradation Their essential properties for operational safety should remain stable throughout the equipment's intended lifespan, unless replacement is planned When choosing materials and manufacturing methods, it is crucial to consider factors such as corrosion and wear resistance, electrical conductivity, impact strength, aging resistance, temperature variations, and the interactions between different materials.
Galvanic corrosion, ultraviolet radiation, and hydrogen degradation significantly impact the mechanical performance of materials For comprehensive guidance on addressing the effects of hydrogen on material performance, refer to ISO/TR 15916 and Annex B.
4.3.4 Where conditions of erosion, abrasion, corrosion or other chemical attack may arise, adequate measures shall be taken to
To mitigate the impact, it is essential to implement suitable design strategies, such as increasing thickness, and to employ effective protective measures, including liners, cladding materials, or surface coatings, while considering the intended and reasonably foreseeable applications.
– permit replacement of parts which are most affected;
It is essential to highlight the type and frequency of inspection and maintenance measures required for the safe continued use of equipment, as outlined in section 7.4.5 Additionally, it should be specified which components are prone to wear and the criteria for their replacement.
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General requirements
Accessible components of the fuel cell power system must be designed to minimize injury risks by ensuring they are free from sharp edges, sharp angles, and rough surfaces.
The design and construction of the fuel cell power system, particularly in areas where individuals may walk or stand, must prioritize safety by preventing slips, trips, and falls.
The design and construction of the fuel cell power system, along with its components and fittings, must ensure stability under anticipated operating conditions, including climatic factors If stability cannot be guaranteed, suitable anchorage methods must be implemented and clearly outlined in the provided instructions.
The design and layout of the moving components in the fuel cell power system must prioritize safety by minimizing hazards In cases where hazards cannot be eliminated, appropriate guards or protective devices should be implemented to prevent any risk of contact that could result in accidents.
The components of the fuel cell power system must be designed to ensure that, during normal operation, there is no risk of instability, distortion, breakage, or wear that could compromise safety.
The design and construction of the fuel cell power system must ensure the prevention of risks associated with gases, liquids, dust, or vapors that may be released during its operation or maintenance, as well as those used in its construction.
4.4.7 All parts shall be securely mounted or attached and rigidly supported The use of shock-mounts is permitted when suitable for the application
All components of the safety shutdown system that could lead to a hazardous event, as determined by the reliability and safety analysis in section 4.9.1, must be acknowledged, certified, or individually tested for their specific intended use.
To mitigate the risk of injury from contact with or proximity to high-temperature external surfaces of the appliance enclosure, handles, grips, or knobs, manufacturers must implement measures to eliminate such hazards associated with the fuel cell power system.
To ensure user safety during the operation of the fuel cell power system, manufacturers must either regulate the temperature of external surfaces, handles, grips, and knobs according to specified limits or install protective devices to prevent accidental contact.
External enclosures, except handles held in normal use
Surfaces of handles, knobs, grips and similar parts which are held for short periods only in normal use
- of moulded material (plastic), rubber or wood
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The maximum surface temperature of external surfaces that may be touched by individuals without personal protective equipment should not exceed specified limits According to Table 3 of IEC 60335-1, the temperatures on walls, floors, and ceilings near a stationary fuel cell power system must remain within 50 °C above the ambient temperature during testing conditions.
The design and construction of the fuel cell power system must minimize airborne noise emissions to meet the requirements of the intended use or location, ensuring compliance with relevant regional or national noise regulations and standards.
4.4.11 The fuel cell power system exhaust to atmosphere, under normal steady-state operating conditions, shall not contain concentrations of carbon monoxide in excess of
300 ppm in an air-free sample of the effluents, which is a sample that has its effluent CO concentration mathematically corrected as though there was zero per cent excess air
4.4.12 Where explosive, flammable, or toxic fluids are contained in the piping, appropriate precautions shall be taken in the design and marking of sampling and take-off points
4.4.13 The maximum temperatures of components and materials, as installed in the fuel cell power system, shall not exceed their temperature ratings
The manufacturer must assess the fuel cell power system's ability to function effectively in environments with contaminants such as dust, salt, smoke, and corrosive gases.
The design of the fuel cell power system enclosure must ensure safe containment of any potential hazardous liquid leaks, as outlined in section 4.5.2f regarding liquid fuel Additionally, the containment system should have a capacity that is 110% of the maximum expected fluid volume that could leak.
Pressure equipment and piping
Pressurized vessels, including reactors, heat exchangers, gas-fired tube heaters, electric boilers, coolers, and accumulators, along with their pressure relief mechanisms like relief valves, must be built and labeled according to relevant regional or national pressure equipment codes and standards.
ISO 16528 provides information concerning pressure equipment standards
Vessels that do not meet the definition of "pressure vessels" under regional or national pressure equipment codes, such as tanks and similar containers, must be made from appropriate materials and comply with specified requirements These vessels, along with their joints and fittings, should be designed and constructed to ensure sufficient strength and leakage resistance, thereby preventing unintended releases.
Piping and its associated joints and fittings shall conform to the applicable sections of
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Piping systems intended for internal gauge pressures ranging from zero to less than 105 kPa, which transport non-flammable, non-toxic fluids that do not harm human tissue, and operate within a design temperature of −29 °C to 186 °C, are excluded from the scope of this regulation.
ISO 15649 specifies that piping systems must be made from appropriate materials as outlined in section 4.3 and must comply with the requirements of section 4.4 The design and construction of these pipes, along with their joints and fittings, should ensure sufficient strength for functionality and leakage resistance, thereby preventing any unintended releases.
The design and construction of rigid and flexible pipes and fittings must adhere to specific requirements Materials should comply with established standards, and internal surfaces must be thoroughly cleaned to eliminate loose particles, with ends reamed to remove obstructions To prevent damage from fluid condensate or sediment in gaseous fluid piping, manufacturers must provide drainage solutions and access for maintenance, particularly in fuel gas controls, where sediment traps or filters are essential Similarly, measures must be taken to prevent sediment accumulation in liquid fuel controls, with appropriate guidelines included in technical documentation Non-metallic piping for combustible gases must be safeguarded against overheating, ensuring temperatures do not exceed design limits Additionally, liquid fuel cell power systems must incorporate features for capturing, recycling, or safely disposing of released liquid fuel, utilizing drip pans, spill guards, or double-walled pipes to prevent uncontrolled releases.
The fuel cell power system must include a vent system to safely expel combustion products into the atmosphere, although small systems (under 10 kW net electrical output) may be exempt from this requirement The manufacturer is responsible for designing the vent pipe or providing detailed instructions for its construction, ensuring compliance with specific material requirements The venting system must be made from corrosion-resistant materials, particularly against condensate, and non-metallic materials should be evaluated for temperature limits, strength, and condensate resistance Additionally, all components of the venting system must be durable to prevent breakage or damage that could compromise the safe operation of the fuel cell power system.
The vent pipe must be adequately supported and equipped with a rain cap to ensure unobstructed vertical gas flow Additionally, drainage systems should be implemented to prevent the accumulation of water, ice, and debris within the vent pipe Exhaust outlets must be positioned outdoors, away from user areas, ignition sources, air intakes, and building openings A leak-tight venting system is essential for fuel cell power systems, and the exhaust outlet collar should accommodate standard vent connectors as per manufacturer instructions Pressure switches for exhaust gas flow verification must be factory set or adjusted by authorized personnel, with adjustments locked and clearly marked Furthermore, components of the pressure switch in contact with exhaust gas condensate must be corrosion-resistant, and the fuel cell power system should remain operational under specified static and velocity pressure conditions.
At a wind velocity of 54 km/h, tests conducted in section 5.14 k) indicate that when a fuel cell power system includes a venting system, the average temperature of the exhaust gases must remain within acceptable limits for the materials used in the venting system's construction.
4.5.4 Gas-conveying parts shall comply with the following condition
Gas passage shall have gas-tightness, so that the tightness shall not be undermined under ordinary transportation, installation, and use.
Protection against fire or explosion hazards
To prevent fire and explosion hazards in fuel cell power systems equipped with cabinets, it is essential to assemble integrated systems that mitigate risks associated with flammable atmospheres The dilution boundary for normal internal releases must be maintained below 25% LEL (Lower Explosive Limit) for hydrogen, which can be determined through computational fluid dynamic analysis or tracer gas methods as outlined in IEC 60079-10 All devices within these dilution boundaries must comply with specified requirements, and the volume should be classified according to IEC 60079-10 Additionally, compartments that contain internal sources of flammable gas or vapor are classified as fuel compartments, which must be designed accordingly.
– maintain gas mixtures below 25 percent LEL (LFL for hydrogen), except in dilution boundaries; and
– limit the extent of dilution boundaries to within the fuel compartment
Licensed to MECON Limited for internal use in Ranchi and Bangalore, this document outlines methods to keep normal internal releases below 25% LEL (Lower Explosive Limit) for hydrogen, except within dilution boundaries.
1) Controlled oxidation of normal internal releases
To achieve effective combustion of released gases, it is essential to provide continuous and reliable sources of ignition and oxidants, or to utilize catalytic oxidation units.
The manufacturer must guarantee that the maximum credible release generates pressures and temperatures that can be safely contained within the fuel compartment and withstanded by the components exposed to these conditions.
2) Air dilution of normal internal releases
Mechanical ventilation can effectively reduce the concentration of normal releases to below 25% of the Lower Explosive Limit (LEL) for hydrogen, provided it remains within specified dilution boundaries Additionally, the minimum ventilation rate must align with the allowable leakage rate test outlined in section 5.4.
Ventilated fuel compartments must be engineered to maintain negative pressure compared to other compartments in the fuel cell power system and its environment, in accordance with IEC 60079-16 The effectiveness of the ventilation system should be verified through flow or pressure measurements In the event of ventilation failure, the process equipment must be shut down to ensure safety.
Fuel compartments in fuel cell power systems do not require ventilation at negative pressures if effective measures are in place to keep the concentration of flammable gas below 25% LFL under all usage conditions, except within specified dilution boundaries.
Fuel compartments that rely on ventilation for protection against accumulation of flammable atmospheres shall be purged in such a way that the atmosphere will be brought below 25 % of the LFL
NOTE One method of accomplishing this is with at least four air exchanges within an appropriate time interval to ensure this result
Purging must occur before energizing any devices that do not meet the area classification requirements If the atmosphere in the compartment and ducts is proven to be non-hazardous by design, purging is unnecessary Any devices that need to be energized before or during purging must comply with specified requirements In hazardous areas, manufacturers must eliminate ignition sources, except for units using the specified protection method.
– installed electrical equipment is suitable for the area classification according to
IEC 60079-0 and other applicable parts of the IEC 60079 series;
– installed electrical resistance trace heating, if available, complies with IEC 62086-1;
Surface temperatures must remain below 80% of the auto-ignition temperature, measured in degrees Celsius, for any flammable gas or vapor For detailed information on the auto-ignition temperatures of different flammable fluids, refer to IEC 60079-20.
– potential for static discharge has been eliminated by proper bonding and grounding according to IEC 60204-1 and by proper material selection;
Equipment designed with materials that can catalyze the reaction of flammable fluids with air must effectively prevent the spread of this reaction to the surrounding flammable environment.
Compartments housing electrical or mechanical equipment must be kept at a positive pressure compared to adjacent areas with flammable gas or vapor, in accordance with IEC 60079-2 standards Additionally, the fuel cell power system must incorporate both passive and active measures, or a combination of both, to ensure that any abnormal internal releases remain below 25% of the Lower Explosive Limit (LEL) for hydrogen, except within dilution boundaries.
In this analysis, sudden and catastrophic failures are not regarded as a release scenario if the vessel and piping design has already incorporated protection against such failures.
Passive means refer to methods that restrict the release of flammable gases or vapors to a predetermined maximum value This can be achieved through the use of pipe orifices, flow restriction techniques, or securely constructed joints designed to limit the release rate predictably.
Active safety measures for fuel cell power systems include flow measurements, controls, and safety devices like combustible gas sensors, which must comply with specified requirements These systems are designed to shut down if flammable gas concentrations in the ventilation exhaust exceed 25% of the lower explosive limit (LEL) for that gas Additionally, the design must ensure safe dispersal of ventilation and process exhaust streams, particularly for indoor installations, which should connect to a flue or venting system It's important to note that non-metallic tubing carrying hydrogen gas can accumulate electrostatic charges, posing a risk of igniting flammable gas mixtures in the environment.
In Zone 1 or Zone 2 locations as defined by IEC 60079-10, it is essential to implement measures to prevent electrostatic discharges This can be accomplished by selecting tubing materials with adequate conductivity or by controlling gas flow velocities to levels that prevent the accumulation of electrostatic charge It is important to avoid using tubing that depends on protective systems, such as grounding wires or braids, to mitigate electrostatic discharge.
Electrical safety
The output voltage of a fuel cell power system must not exceed 600 V a.c or 600 V d.c However, higher output voltages are allowed if they comply with the relevant local or national standards for those voltage ratings.
Electrical terms and definitions used in this standard are the same as those given in
4.7.1 Protection against electric shock and energy hazards
IEC 60950-1, 2.1.1.2, 2.1.1.4, 2.1.1.5, 2.1.1.6, and 2.1.1.7 apply together with the following
Electrical disconnect devices must include a mechanism for physically locking the disconnect lever This feature is essential to ensure the safety of service personnel by preventing accidental reconnection before the servicing process is fully completed.
The provisions of 2.10 of IEC 60950-1 apply to clearances, creepage distances and distances through insulation
IEC 60950-1, Clause 3, applies to wiring connection and supply
This standard specifies two categories of requirements for protection against electric shock from energized parts
Operators are allowed access to bare components in SELV circuits, bare parts in limited current circuits, and the insulation of wiring in ELV circuits, provided that the conditions outlined in 60950-1, section 2.1.1.3, are met.
The operator shall be prevented from having access to a) bare parts of circuits at ELV or hazardous voltages;
This document is licensed to MECON Limited for internal use in Ranchi and Bangalore, as supplied by the Book Supply Bureau It outlines the conditions for operational or basic insulation of specific components, particularly emphasizing that unearthed conductive parts must be isolated from parts operating at extra-low voltage (ELV) or hazardous voltages solely through operational or basic insulation.
IEC 60950-1, 2.1.1.3, applies together with consideration for the maximum unsynchronized voltages that may appear across the line and inverter terminals
4.7.1.3 Discharge of capacitors in the primary circuit
IEC 60950-1, 2.1.1.7, applies together with consideration for capacitance stored in the load as well as internal circuitry
The fuel cell generator must include a built-in emergency switching device or terminals for connecting a remote emergency switch, ensuring that power supply to the load is halted in all operational modes If the building's wiring system is expected to provide additional disconnection, this requirement should be clearly outlined in the installation instructions.
Plug-connected fuel cell generators do not require an emergency switching device if the plug can perform the same function
The following apply to electrical components within the equipment
Components shall comply either with the requirements of this standard or with the conditions of the relevant IEC component standards
Components intended for connection to both SELV and ELV circuits, or to parts with hazardous voltage, must meet the requirements for SELV circuits A typical example of such a component is a relay that has different power supplies linked to various elements, including coils and contacts It is essential to evaluate and test these components to ensure compliance and safety.
A component that meets the relevant IEC component standard must be verified for proper application and usage according to its rating It should undergo the necessary tests outlined in this standard, excluding those tests specified in the corresponding IEC component standard.
Any component that has not been proven to meet the relevant standard must be verified for proper application and usage according to its specified rating It should undergo the necessary tests outlined in this standard, as part of the overall equipment, as well as the relevant tests of the component standard, under the conditions present in the equipment.
NOTE The applicable test for compliance with a component standard is, in general, carried out separately
In the absence of a relevant IEC component standard, or when components are utilized in circuits that do not align with their specified ratings, it is essential to test these components under the actual conditions present in the equipment Typically, the number of samples needed for testing should match the requirements outlined in an equivalent standard.
Thermal controls shall meet the requirements of 1.5.3 of IEC 60950-1
Transformers shall comply with the requirements of 1.5.4 of IEC 60950-1
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Capacitors connected across line power shall comply with 1.5.5 of IEC 60950-1 b) Components that bridge double or reinforced insulation
It is permitted to bridge double insulation or reinforced insulation by
1) a single capacitor complying with IEC 60384-14:1993, subclass Y1;
A single capacitor that meets the IEC 60384-14:1993 standard, subclass Y2, is suitable for equipment with a rated voltage of less than 150 V relative to neutral or earth Alternatively, two capacitors can be connected in series, with each capacitor conforming to either the Y2 or Y4 subclass of the IEC 60384-14:1993 standard.
A Y1 or Y2 capacitor, when used as specified, is deemed to possess reinforced insulation In cases where two capacitors are connected in series, both must be rated for the total working voltage across the combination and should have identical nominal capacitance values.
It is permitted to bridge double insulation or reinforced insulation by two resistors in series The resistors shall each comply with the requirements of 2.10.3 and 2.10.4 of
IEC 60950-1 for basic insulation or supplementary insulation, as applicable, between their terminations for the total working voltage across the pair and shall have the same nominal resistance value
Where accessible conductive parts or circuits are separated from other parts by double insulation or reinforced insulation that is bridged by components in accordance with
According to sections 1.5.7.2 and 1.5.7.3 of IEC 60950-1, accessible parts or circuits must adhere to the limited current circuit requirements outlined in section 2.4 of the same standard These requirements are applicable following the completion of electric strength testing of the insulation.
– Components in equipment for unearthed power distribution systems
Equipment connected to unearthed power distribution systems must have components that can endure the stress from line-to-line voltage Nevertheless, capacitors rated for the relevant line-to-neutral voltage are allowed in these applications, provided they meet the standards set by IEC 60384-14:1993, specifically subclasses Y1 or Y2.
The steady-state input current of the equipment shall not exceed the rated current by more than 10 % under normal load
NOTE See also 1.4.10 of IEC 60950-1
Compliance is checked by measuring the input current of the equipment at normal load under the following conditions
The normal load for systems powered by an external mains source is defined as the maximum load connected to the mains, which is essential for idling, starting, or maintaining the operation of the power system.
– Where an equipment has more than one rated voltage, the input current is measured at each rated voltage;
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When equipment features multiple rated voltage ranges, the input current is measured at both ends of each range If a single rated current value is indicated, it applies to the entire equipment.
Electromagnetic compatibility (EMC)
The fuel cell power system must not produce electromagnetic disturbances that exceed acceptable levels for its designated applications Additionally, it should possess sufficient immunity to electromagnetic disturbances to ensure proper operation in its intended environment Compliance with relevant standards, including IEC 61000-3-2, IEC 61000-3-3, IEC 61000-3-4, and IEC 61000-3-5, is required for the fuel cell power system.
IEC 61000-6-1, IEC 61000-6-2, IEC 61000-6-3, and IEC 61000-6-4.
Control systems and protective components
4.9.1.1 The safety and reliability analysis as specified in 4.1.2 shall provide the basis to set the protection parameters of the safety circuit
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The design of the fuel cell power system must ensure that the failure of any single component does not lead to a hazardous situation To achieve this, various measures should be implemented to prevent cascading failures.
– protective devices in the fuel cell power system (for example, interlocking guards, trip devices);
– protective interlocking of the electrical circuit;
– use of proven techniques and components;
– provision of partial or complete redundancy or diversity; and
Guidance for the design of electrical, electronic and programmable controls can be found in
Automatic controls for fuel cell power systems must be designed for safety and reliability Fuel cell systems used in residential, commercial, and light industrial applications should comply with IEC 60730-1 standards.
Automatic electrical burner control systems shall comply with IEC 60730-2-5
Automatic electrical control systems for catalytic oxidation reactors shall comply as applicable with IEC 60730-2-5 Specific requirements are provided in 4.6.3
Manual controls shall be clearly marked and designed to prevent inadvertent adjustment and activation
In particular, the following requirements apply
The start of an operation shall be possible only when all the safeguards are in place and are functional
Suitable interlocks shall be provided to secure correct sequential starting
Automated plant operations can be resumed in automatic mode after a stoppage, once safety conditions are met Additionally, the fuel cell power system can be restarted through a designated control, ensuring that the process is verifiably safe.
This requirement does not apply to the restarting of the fuel cell power system resulting from the normal sequence of an automatic cycle
As determined by the reliability assessment indicated in 4.1.2 and the functional requirements of the fuel cell power system shall be provided with the following shutdowns
A safety shutdown occurs when the main fuel flow is de-energized during air-rich operations, or when both the process air flow and main fuel flow are de-energized in fuel-rich operations This action is triggered by a limiter, a cut-out, or the detection of an internal system fault.
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A controlled shutdown involves de-energizing the main fuel flow for air-rich operations, or both the process air flow and main fuel flow for fuel-rich operations, triggered by a control device like a thermostat This process effectively resets the system to its initial state.
Safety shutdowns are essential components of fuel cell power systems, designed to prevent actual or potential hazards that cannot be mitigated through standard controls.
– stop the dangerous condition without creating additional hazards;
– trigger or permit the triggering of certain safeguard actions where necessary;
– override all other functions and operations in all modes;
– prevent reset from initiating a restart;
Restart lock-outs must be implemented to ensure that a new start command can only be activated after the intentional reset of these lock-outs during normal operation Additionally, an emergency stop feature is essential for safety.
Manual safety shutdowns, or emergency stops, must be equipped with controls that are easily identifiable, highly visible, and quickly accessible, such as buttons, as mandated by ISO 13850 Additionally, it is essential to implement control functions to address potential failures in control systems.
In case of fault in the control system logic or failure of, or damage to, the control system hardware,
– the fuel cell power system shall not be prevented from stopping once the stop command has been given;
– automatic or manual stopping of the moving parts shall be unimpeded;
– the protection devices shall remain fully effective;
– the fuel cell power system shall not restart unexpectedly
In the event of a safety shutdown triggered by a protective device or interlock in the fuel cell power system, the control system must be notified of this condition It is crucial that resetting the shutdown function does not lead to any dangerous situations Additionally, control and monitoring systems capable of functioning safely during hazardous conditions may remain powered to ensure the availability of system information.
In situations where upset conditions can be safely managed and do not present an immediate threat, a controlled shutdown can be implemented This process may involve completely cutting off power to the equipment or maintaining power to the actuators of the fuel cell power system.
Permissives must be implemented in accordance with the safety and reliability analysis outlined in section 4.1.2 A permissive is a condition within a logic sequence that must be met before advancing to the next phase of the process.
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When designing a fuel cell power system to operate alongside other equipment, it is essential to implement stop controls, including an emergency stop feature These controls should include signal interfaces that facilitate a coordinated shutdown with both upstream and downstream equipment, ensuring safety in case continued operation poses a danger.
4.9.2.5 Operating modes a) There shall be two primary operating modes: ON and OFF
In the ON-mode, the components of the fuel cell power system are fully operational and actively supplying power Additionally, certain conditions are classified as ON-modes.
– standby state (zero net power output);
– automatic start enabled (power left available to the power system actuators)
In OFF-mode, the fuel cell power system will have all power cut, rendering the unit inactive, although minimal power may be supplied to prevent component deterioration The two main transitions for the system are start-up and shutdown.
Start-up is the transition from OFF to ON and shall be initiated from an external signal
Shutdown refers to the automatic switch from ON to OFF, which can be triggered by either an external signal or an internal signal due to conditions exceeding the limits of the fuel cell power system controller Additionally, secondary operating modes and transitions may be implemented to accommodate varying power output rates or to facilitate adjustment, maintenance, or inspection activities Mode selection is also an important aspect of this process.
Pneumatic and hydraulic powered equipment
Pneumatic and hydraulic equipment of fuel cell power systems shall be designed according to
Valves
Shut-off valves are essential for all equipment and systems that require the containment or blockage of process fluid flow during shutdowns, testing, maintenance, emergencies, or upset conditions These valves must be rated appropriately for the specific service pressure, temperature, and fluid characteristics involved.
Actuators on shut-off valves must be temperature-rated to endure heat from the valve body Additionally, shut-off valves that are electrically, hydraulically, or pneumatically operated should be designed to move to a failsafe position in the event of a loss of actuation energy.
Supply fuel valves must adhere to specific standards: a) All fuel directed to the fuel cell power system must pass through a minimum of two automatic valves in series, functioning as both operating and safety shutoff valves b) Fuel supplied directly to fuel-fired equipment, such as startup boilers or reformer start burners, must also go through at least two automatic valves in series, serving the same dual purpose These valves may be housed within a single control body c) Electrically operated supply fuel valves are required to comply with IEC 60730-2-17 standards.
According to IEC 60730-2-19, when fuel gases are recycled from appliances utilizing the fuel cell power system output gas, the connection may not require shutoff valves if it is proven to be safe through the safety and reliability analysis outlined in section 4.1.2.
Rotating equipment
Rotating equipment must be designed to withstand the specific pressures, temperatures, and fluids encountered during normal operations It is essential to protect fluid inlet and outlet lines from vibration damage Shaft seals should be compatible with the fluids being pumped and the anticipated operating conditions, including both normal and emergency shutdowns, to prevent hazardous fluid leakage In cases where leakage is possible, manufacturers must implement containment or dilution measures to mitigate health and safety risks Additionally, motors, bearings, and seals must be appropriate for the expected duty cycles.
4.12.2.1 Where appropriate, packaged compressors shall conform to one of the following standards: ISO 5388:1981; ISO 10439:2002; ISO 10442:2002; ISO 13707:2000; ISO 10440-
Compressors and compressor systems must be equipped with essential safety features unless deemed unnecessary by a safety and reliability analysis These features include pressure-relief devices to maintain stage pressure within the maximum operating limits of the compression cylinder and associated piping, an automatic shutdown control for high discharge and low suction pressure, and, when necessary, an unloading device that captures and recycles blow-down gas for reuse or safe venting during restart after shutdown.
This document is licensed to MECON Limited for internal use in Ranchi and Bangalore, as supplied by the Book Supply Bureau It includes essential measures such as implementing vibration isolation between the inlet pipe and the compressor suction line, as well as incorporating a pressure-limiting device to prevent over-pressurization at the inlet.
4.12.2.3 Compressors excluded from the scope of the standards referenced in 4.12.2.1 due to small capacity or low discharge pressure need only comply with the requirements specified in 4.12.2.2
Packaged low-discharge pressure compressors (fans and blowers) shall be guarded according to ISO 12499 (see also 4.4.4)
4.12.3.1 Packaged electric pumps for process liquids shall conform to ISO 13709 or ISO
Packaged electric pumps for water shall conform to IEC 60335-2-51 if applicable
Electric pumps and their systems must include essential features for safe operation These include pressure-relief devices that ensure both inlet and outlet pressures remain below the design pressure of the piping, although relief valves are not necessary if the pump's shutoff head is lower than the piping's pressure rating Additionally, an automatic shutdown control is required to manage high discharge pressure Furthermore, it is crucial to protect suction and discharge lines from potential damage caused by vibration.
4.12.3.3 Pumps excluded from the scope of the standards referenced in 4.12.3.1 due to small capacity or low discharge pressure need only comply with the requirements specified in
Cabinets
Fuel cell power system cabinets must possess adequate strength, rigidity, and durability, along with resistance to corrosion and other physical properties These attributes are essential to support and safeguard all components and piping of the fuel cell power system, ensuring compliance with the requirements for storage, transport, installation, and final placement conditions.
Fuel cell power system cabinets designed for indoor use or protected outdoor locations must comply with a minimum IP22 rating as specified by IEC 60529.
The fuel cell power system designed for non-weather-protected outdoor locations must start and function properly without any damage or malfunctions that could lead to hazardous conditions This requirement is validated through a simulated rain test in accordance with IEC 60529, specifically under test condition 14.2.4a.
4.13.4 Ventilation openings shall be so designed that they will not become obstructed during normal operation either by dust, snow or vegetation in accordance with the expected application
All materials utilized in cabinet construction, including joints, vents, and door gaskets, must be durable enough to endure the expected physical, chemical, and thermal conditions throughout the lifespan of the fuel cell power system.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
Access panels, covers, or insulation intended for regular servicing and accessibility must be designed to withstand repeated removal and replacement without causing damage or reducing their insulating effectiveness.
4.13.7 Access panels, covers or insulation that need to be removed for normal servicing and accessibility shall not be interchangeable if that interchange may lead to an unsafe condition
Access panels, covers, or doors designed to safeguard equipment from unauthorized entry must be securely retained and require a tool, key, or similar mechanism for opening This requirement applies to all residential units.
All components of fuel cell power systems that are configured during manufacturing and are not intended for user or installer adjustment must be properly safeguarded.
4.13.10 Means shall be provided to drain collected liquids and to pipe them to the exterior for disposal or redirect them to processes associated with the fuel cell power system
4.13.11 Where personnel can fully enter the cabinet, the cabinet shall be considered a confined space and adequate guidelines shall be provided in the product’s technical documentation.