BRITISH STANDARD BS EN 50123 2 2003 Railway applications — Fixed installations — D C switchgear — Part 2 D C circuit breakers The European Standard EN 50123 2 2003 has the status of a British Standard[.]
Enumeration of the characteristics
The characteristics of a circuit breaker and its assigned designations and values (where applicable) are covered below as follows:
• rated values and limit values of the main circuit and short-circuit characteristics (5.3);
Type of circuit breaker
A circuit breaker is defined by the following details, as applicable
NOTE 1 As far as applicable, the following requirements also apply to single-pole circuit breakers electrically or mechanically interlocked in multiple systems a) Interruption:
This standard specifically addresses interruptions in air or through a semiconductor, but it can also be applied to other specified interrupting media if mutually agreed upon by the purchaser and supplier Additionally, it includes breaking characteristics that are designated by class.
• high speed current limiting circuit breakers H;
• very-high speed current limiting circuit breakers V;
• semi-high speed circuit breakers S c) Use (installation point) in the system:
• interconnector circuit breaker I (also called bus-section or section circuit breaker);
• rectifier circuit breaker R d) Current interruption direction:
- fitted with a series unidirectional release U 1 ;
- fitted with a series bidirectional release U 2
NOTE 3 U 2 circuit breakers are designed for applications with low reverse fault currents, such as in substations where adjacent substations are located at a significant distance These circuit breakers are essential for ensuring proper overload protection and maintaining normal discrimination in such scenarios.
• bidirectional B e) Duty of the main circuit
NOTE 4 To be specified when different from 5.3.4.2 and Table 2 f) Actuating of the closing and opening operations:
• type of automatic tripping due to a release or relay;
• interlocks for opening and/or closing operations;
• anti-pumping device g) Relay or release type:
• type of the relay(s) or release(s) involved h) Provision of an enclosure:
• without provision of an enclosure O (see 3.3.16 of EN 50123-1);
• with provision of an integral enclosure E (see 3.3.17 of EN 50123-1);
• with provision of a separate protection enclosure P
The buyer must specify the desired features for the circuit breaker(s), and only the tests relevant to the selected type will be applicable.
The above designations are used in this standard and may be used elsewhere adopting the conventional grouping as given in Table 1:
When a circuit breaker is deemed unsuitable for all duties specified in section 5.3.4.2, this will be indicated by lowercase letters representing its actual capability, as outlined in Table 2, first column (e.g., H/Iff, fr/P) Additionally, if a circuit breaker is suitable for multiple alternate functions, these functions will be prefixed with "and."
Semiconductor circuit breakers intended solely for rectifier-equipped substations must be clearly labeled as such If these breakers can also function as track paralleling circuit breakers when the substation rectifier circuit breakers are not in operation, this capability should also be distinctly marked.
Rated values and limit values for the main circuit
The purchaser must specify the rated characteristic values, including nominal voltage, which should be chosen from the values in Table 1 of EN 50123-1 Additionally, current values and track time constant should be selected based on the track configuration that yields the largest track time constant, adhering to the preferred values outlined in section 5.1.2 of EN 50123-1.
These values should be confirmed by the supplier, who should indicate the rated values for the type of circuit breaker proposed and supply any other relevant data
All these values are to be stipulated in accordance with 5.3.2 to 5.3.4 Definitions are given in
EN 50123-1 Some data may be omitted by agreement
A circuit breaker is identified by the following voltages:
• system voltages and limits (see 3.2.1 and 5.1.3 of EN 50123-1);
• rated voltage U Ne (see 3.2.3 of EN 50123-1);
• rated insulation voltage U Nm (see 3.2.2 of EN 50123-1) It shall be equal to or higher than
• rated impulse withstand voltage U Ni (see 3.2.4 of EN 50123-1);
• power-frequency voltage withstand level (dry) U a (see 3.2.5 and Table 1 of EN 50123-1);
• maximum arc voltage (see 3.2.6.1 of EN 50123-1);
• rated auxiliary and control supply voltages (see 3.2.3.1 of EN 50123-1)
A circuit breaker is defined by the following currents:
• conventional thermal current I th, I the (see 3.2.8 and 3.2.9 of EN 50123-1);
• rated service current I Ne (see 3.2.10 of EN 50123-1);
• rated short circuit current I Nss (see 3.2.12.1 of EN 50123-1);
• rated short-time withstand current I Ncw (see 3.2.11 of EN 50123-1)
Short-time ratings are applicable exclusively to circuit breakers that do not have series trip devices or in unidirectional devices where the series trip is non-functional This situation typically arises in rectifier circuit breakers operating in the forward direction, where the series trip mechanism only activates in the reverse direction.
NOTE 2 Rated short-time currents donot need to have the same value as the rated short-circuit current
• overload capability: the purchaser shall inform the supplier of the load cycle requirements (see 3.2.10, note 2 of EN 50123-1)
5.3.4.1 Rated short-circuit breaking and making capacities
The values specified in sections 3.2.19 and 3.2.23 of EN 50123-1 relate to the rated voltage (U Ne), rated service current (I Ne), rated short-circuit current (I Nss), rated track time-constant (T Nc), and the class designation (H, V, or S).
The rated short-circuit making capacity is the prospective peak value of the rated short-circuit current I Nss (see 3.2.12.1 of EN 50123-1)
A circuit breaker must possess a rated short-circuit breaking capacity that allows it to interrupt any short-circuit current equal to or less than this specified capacity, adhering to the designated time constant.
A circuit breaker having a breaking capacity at a rated track time constant T Nc is capable of the same breaking capacity at all lower values of track time constant T c
The prospective maximum short-circuit current is the sum of the prospective short-circuit currents from all sources connected to the system, including rectifier converters and regenerative trains
When fixing the maximum short-circuit current and the above track time constant, clause 5 of
5.3.4.2 Duties and test duty cycles
The duties required of a circuit breaker for each of the three uses are listed in Table 2 The test duty cycles applying to the duties are shown in Table 3
When a manufacturer or supplier provides a circuit breaker with short circuit breaking characteristics that exceed the installation's actual requirements, the purchaser and supplier may agree to conduct additional tests as per section 8.3.8 for specific duties These tests will utilize the actual required test current and can be performed at a standard test duty cycle.
1 or duty 2) or at an agreed duty cycle and may be repeated a number of times upon agreement between purchaser and supplier
Duty Use Conditions Test current Prospective peak Time constant f L Maximum fault I Nss ≥ 1,42 I Nss By consequence of other circuit parameters e L a Maximum energy 0,5 I Nss By consequence of other circuit parameters
0,5 T Nc d L Distant fault 2 I Ne By consequence of other circuit parameters
The low current threshold, denoted as \$I_c\$, is approximately 0.01 seconds, and the maximum fault forward current, \$I_{Nss}\$, must be greater than or equal to 1.42 due to other circuit parameters Similarly, the maximum fault reverse current, \$I_{Nss}\$, also requires a minimum of 1.42 as a result of other circuit parameters Additionally, \$R_b\$ represents the forward low current following a reverse short circuit.
I c Not applicable ≅ 0,01 s r R Max fault reverse with paralleled converters I Nss ≥ 1,42 I Nss s R Short time current forward I Ncw ≥ 1,42 I Ncw
NOTE 1 For substations equipped with smoothing reactors of high value, the maximum energy condition may correspond to the maximum fault condition
NOTE 2 I Nss is to be determined for each type of actual circuit situation Therefore I Nss may be different for Line
The L, Interconnector I, and Rectifier R circuit breakers are influenced by a factor of 0.5 for both I Nss and T Nc at the maximum fault position, chosen for practical considerations For low values of T Nc, refer to Table 2 in section 5.1.1.3 of EN 50123-1 The use of R is only necessary when specifically requested by the purchaser.
O - 7 s - CO - 10 s - CO - 60 s - CO ff, fr, r O - 15 s - CO l, lr 10 times (O - 120 s - CO) s Carrying for 0,25 s
NOTE 1 O = opening operation; C = closing operation
The initial opening occurs when a short circuit is established The purchaser has the option to select either duty cycle 1 or 2; if no selection is made, duty cycle 1 will be applied by default.
Circuit breakers intended for multiple duties must undergo comprehensive testing for each duty, unless an alternative agreement is made between the purchaser and supplier These tests should be conducted on a single circuit breaker, which can be maintained between duty cycles Additionally, any subsequent duty cycles on the same circuit breaker require adequate cooling time for the components before proceeding.
The tests will be conducted with the series overcurrent release adjusted to its maximum setting, specifically four times the rated current (I Ne, I th, or I the) for test duties f, e, ff, fr, and 0.5 times for test duties r and s.
For test duties d) and l), the circuit breaker must trip once the sustained value is achieved Specifically for test duty d), the trip should be activated when the track time constants are prolonged.
Control circuits
The control circuits are identified by the following characteristics as a minimum:
• the voltage of the control circuits;
• the kind of current (d.c or a.c.);
• the current frequency, in case of an a.c current
The voltage of the supply source and its frequency are the values on which the performances, the thermal behaviour and the insulation characteristics are based
Unless otherwise required, the voltage shall be in accordance with 5.2 of EN 50123-1 and rated insulation voltage shall be in accordance with EN 50124-1
The supply voltage shall be within a range between 80 % and 110 % of the voltage in accordance with 5.2 of EN 50123-1
Where the control voltage is the same as in the main circuit, the same variations as in the main circuit apply
The manufacturer must specify the current values drawn by the control circuits at the rated voltage For control circuits that draw current intermittently, the duration of the current flow should also be provided.
Auxiliary contacts and circuits
Auxiliary circuits are characterized by the number of contacts, their thermal current and voltage ratings, and their specific features, such as normally open (NO), normally closed (NC), or commutation The rated voltage must comply with section 5.2 of EN 50123-1, while the rated insulation voltage should adhere to EN 50124-1 standards.
The purchaser shall specify the minimum number of auxiliary contacts required
The auxiliary wiring connected to a circuit at 1 000 V a.c or at 1 500 V d.c or above shall be physically separated from those connected to a circuit at a voltage below said limits
For other characteristics of the auxiliary circuits, the requirements of 5.4 apply.
Releases
NOTE The following requirements apply for direct or indirect releases which are part of the circuit breaker
Classification of the releases comprises
• series (direct or indirect) overcurrent releases,
A release may be instantaneous, time-lagged or time-dependant, or a combination of all three Other characteristics are as follows: a) for overcurrent (d.c.) releases:
• type (overcurrent direct or indirect);
• the setting current (or setting range);
• the direction of the main carrying current in case of a unidirectional circuit breaker;
• characteristics of the operating time which the release gives the circuit breaker as a function of the rate of rise of the current
The release shall be capable of withstanding this current under the test conditions specified in clause 8, without the temperature-rise exceeding the values specified in clause 6 of EN 50123-1
Circuit breakers with interchangeable or adjustable releases must display the current setting or setting range on the release or its scale, indicated in amperes or multiples of the current The purchaser is responsible for specifying the desired setting range, ensuring that the ratio of minimum to maximum values does not exceed 1:2 under normal conditions.
• the power taken at the rated voltage for a specified time.
Arc voltage
The manufacturer shall specify the maximum value of the arc voltage Û arc caused by the operation of the circuit breaker when it is tested in accordance with clause 8
NOTE This maximum voltage is the peak voltage measured during any test duty and is not necessarily seen with maximum current
The maximum value must not surpass the rated impulse withstand voltage of the equipment or four times the nominal voltage If the purchaser requires lower arc voltages, these specifications should be clearly stated.
General
All necessary apparatus and connections for the safe and effective operation, control, and protection of the equipment must be supplied, regardless of whether they are explicitly mentioned, unless an agreement is made between the circuit breaker and switchgear assembly manufacturers The equipment should be properly earthed, insulated, screened, or enclosed as needed to ensure both the protection of the equipment and the safety of personnel involved in its operation and maintenance.
Control and auxiliary circuits and contacts shall comply with the requirements of 5.2 of
No materials containing asbestos shall be used in the construction of the circuit breaker
When selecting materials, it is crucial to prioritize their moisture and fire resistance properties The materials should be self-extinguishing to minimize the risk of fire spreading between cubicles, as outlined in Annex B of EN 50123-1.
Arcing contacts, if any, which are liable to be consumed during arc interruption shall be easy to replace
Clearances and creepage distances shall not be lower than those indicated in Table 1 in
EN 50123-1 and in Annex D of EN 50123-1 respectively
Clearances and creepage distances may need to be increased to account for foreign substances that accumulate after numerous operations, both under normal and short circuit conditions, throughout the equipment's lifespan between cleaning procedures.
Where applicable, ribs shall be provided in order to break the continuity of conducting deposit which occurs during operation
The circuit breakers shall be equipped with fixed, removable (bolted or clamped) or plug-in coupling connections
6.1.5 Location of the primary connections
Non-withdrawable circuit breakers must have their primary connection terminals accessible while in the normal operating position The placement of these terminals should be mutually agreed upon by the purchaser and supplier, unless specified by a European standard.
For withdrawable circuit breakers, the terminals for the primary connections shall be accessible in the conditions detailed in EN 50123-6
The frames, structure, and fixed components of metallic enclosures must be interconnected and connected to an accessible earthing terminal to facilitate proper earthing.
NOTE 1 This condition may be fulfilled by normal construction elements, ensuring an adequate electric continuity
For withdrawable circuit breakers, the earth connection shall be made before the shutters are opened, and the shutters shall be closed before the earth connection is disconnected
The purchaser may need a dedicated earth connection For non-dedicated earth connections using bolts or similar fixings, maintenance instructions must specify the cleaning requirements for surfaces and ensure that all connections are tight.
The earthing terminal shall be protected against corrosion The standard earth symbol shall be permanently marked
The earth terminal shall be capable of carrying the rated earth fault current I Ncwe for 0,25 s
NOTE A handle may be required by the purchaser or provided by the supplier for closing during maintenance The handle may be fixed or removable
A fixed handle must remain inaccessible to the operator until the circuit breaker is completely withdrawn from its enclosure or until all primary connections are disconnected.
Circuit breaker enclosures
Circuit breaker enclosures shall conform to EN 50123-6.
Temperature-rises
The temperature shall not rise by more than the values given in clause 6 of EN 50123-1
The main circuit of a circuit breaker, including the series releases and associated relays, must endure its rated currents I Ne, I th, or I the Additionally, it should meet the load cycle requirements as specified by the purchaser, as referenced in note 2 of section 3.2.10 of EN 50123-1.
Control circuits and devices responsible for the operation of circuit breakers must operate within the specified rated temperature-rise limits to ensure safety and efficiency during opening and closing operations.
Auxiliary circuits and devices must endure their specified thermal current for switching devices or their rated service current for other equipment, ensuring that the temperature rise remains within the designated limits.
Dielectric strength
Dielectric strength shall conform to the values stipulated in Table 1 in EN 50123-1.
Electrical and mechanical endurance
The circuit breaker must demonstrate its ability to perform a specified number of operations as outlined in sections 7.3.2 and 7.3.3 of EN 50123-1 Specifically, for the assessment of mechanical endurance, it should complete the required operating cycles without any current flowing through the main circuit.
When L circuit breakers are needed for approximately one operation per day, a specification of 10,000 operating cycles is acceptable; otherwise, the standard is 20,000 cycles For assessing electrical endurance with the rated service current I Ne in the main circuit, specific operating cycles must be conducted.
The test will involve performing the specified number of operating cycles in groups of at least 20 CO operations, with intervals not exceeding 180 seconds This procedure applies to current ratings that are higher than the specified threshold.
4 000 A, the group number may be reduced subject to agreement between purchaser and supplier.
Operation
The closing device, along with any auxiliary control relays, must function properly across all specified voltage levels of the supply source and under any operational conditions of the circuit breaker.
The circuit breakers shall be, unless otherwise specified, trip-free
Relays are covered by this subclause only if fitted to the circuit breaker
6.6.2.2 Opening due to overcurrent relay or release
A new circuit breaker must have its release or relay function operate with a minimum accuracy of ± 5% of the set operating point for electronic types, and ± 10% for electromagnetic types, across the entire current range.
6.6.2.3 Opening due to shunt release
A shunt release must function properly across all specified supply voltage values, as outlined in section 5.4 It should also remain operational with a reduction of up to 15% below the rated operating voltage, regardless of the circuit breaker's operating conditions, up to its breaking capacity.
6.6.2.4 Opening due to undervoltage relay or release
An undervoltage relay is designed to open a circuit breaker when the voltage drops slowly, specifically when it falls between 70% and 35% of its rated value.
An undervoltage relay is designed to prevent a circuit breaker from closing when the supply voltage falls below 35% of its rated voltage, while still allowing closure if the supply voltage is at least 85% or higher.
NOTE A relay or release for loss of voltage is a particular type of undervoltage relay or release for which the operating voltage is between 35 % and 10 % of the rated supply voltage.
Corrosion protection
Steelwork and equipment materials must be treated with an approved corrosion protection method, excluding arc-extinguishing sheets in the arc chute If purchasers have specific requirements, the supplier must either adhere to these specifications or provide an equivalent alternative.
Noise emission
To minimize noise emissions from all equipment, suppliers must provide the noise level during the breaking of the rated service current, I Ne, upon request from the purchaser.
Cooling
Unless otherwise agreed between purchaser and supplier, all equipment is expected to be naturally cooled.
Servo-control (where applicable)
The servo-control shall be mounted either on the circuit breaker or on a structure on which the circuit breaker is also mounted The structure shall be earthed
It shall not be possible for a fault in the servo-control to prevent the opening of the circuit breaker by a manual, electric or automatic control.
Other facilities
Circuit breakers must be equipped with essential features, including a latching device that can be electrical, magnetic, or mechanical Additionally, they should have a mechanical indicator linked to the moving contact or an equivalent method to show the circuit breaker's "closed" and "open" states, typically represented by the symbols "I" and "O."
"ON" and "OFF" shall be used to indicate the closed and open positions respectively; c) means for earthing the circuit breaker structure either through a moving contact or a terminal
Circuit breakers shall have the following facilities, when specified by the purchaser: a) means of closing manually for maintenance; b) operation counter;
NOTE These facilities may be supplied as standard by the manufacturer
Manufacturers must supply two extra auxiliary switch contacts for remote control and monitoring circuits, in addition to the required contacts for normal operating circuits of the circuit breaker Any additional contacts and their types will be determined through an agreement between the purchaser and the supplier.
Information
The purchaser and supplier must share essential information to ensure the circuit breaker meets the intended requirements General details are outlined in clause 5, while specific features and alternative options are discussed in clause 6 A summary of this information can be found in Annex A.
Marking
Each circuit breaker shall be indelibly marked
Circuit breakers must display specific information either directly on the device or on attached rating plates This includes the manufacturer's name or trademark, a reference to the relevant European Standard, type designation, serial number, year of manufacture, rated voltages (U Ne), auxiliary and control supply voltages, rated service/thermal currents (I Ne, I th, or I the), rated short-circuit breaking capacity, rated track time-constant (T Nc), and rated short-time withstand current (I Ncw) if applicable Additionally, the input and output terminals should be marked unless they are interchangeable, and the earth terminal must be indicated by a symbol if relevant The range of settings for releases (A or V) and any compliance with service requirements that differ from the normal standards should also be noted, potentially on a separate label for clarity.
All necessary labelling shall be provided for the purposes of safety, identification, instruction and information Lifting attachments shall be marked
The circuit breaker must display its serial number and type designation in the test position after installation, while other markings should be visible prior to installation Additionally, manufacturers may include an extra rating plate on the circuit breaker enclosure to highlight essential data.
General
General requirements concerning tests are shown in clause 7 of EN 50123-1
NOTE For procedural matters not covered either in this standard or in EN 50123-1, reference may be made to other European or IEC publications covering similar equipment
Tests will be conducted at the specified service values of current, voltage, frequency, and air pressure, unless stated otherwise This requirement applies to the entire circuit breaker, including the main, control, and auxiliary components, in accordance with the values outlined in clause 5.
The test variables shall be within the tolerances indicated in Table 6 of EN 50123-1.
Applicable tests and test sequence
The applicable tests are summarised in Table 4, and tests shall be performed in the order given in Table 4 for each sequence group
Table 4 - List of applicable tests and sequence
Group Test description Kind Reference to subclause
Verification of conformity to the manufacturing drawings and to characteristics of the circuit breaker Type and routine 8.3.1
Mechanical operation Type and routine 8.3.2
Dielectric withstand Type and routine 8.3.3
Verification of the adjustment of the relays and releases Routine 8.3.5
Verification of the making and breaking characteristics in short circuit conditions and of the H, V or S characteristic Type 8.3.8
Verification of the short-time withstand current of rectifier circuit breakers R
Verification of the adjustment of the relays and releases Type 8.3.5
3 Search for critical currents and low current test duty Type 8.3.10
Performance of tests
8.3.1 Verification of the conformity to the manufacturing drawings and the characteristics of the circuit breaker
8.3.1.1 Verification of the conformity to the manufacturing drawings
The circuit breaker to be tested shall respect in all essential details the drawings of the represented type
8.3.1.2 Measurement of the resistance of the main circuit
Resistance measurements of the main circuit shall be made with the circuit breaker at ambient temperature
NOTE This measurement is also required both before and after each short circuit test (see 8.3.8 and 8.3.9)
8.3.1.3 Measurement of the resistance of the coils at ambient temperature
Measurements shall be taken at ambient temperature and shall be corrected to a measurement for a temperature of 35 °C
This test is carried out at the laboratory ambient temperature, in accordance with 7.3.1 of
• one satisfactory opening of the circuit breaker, while the closing device is energised (trip- free operation, see 3.4.11 of EN 50123-1) (if this feature is provided);
• that the closing operation is not completed when the closing operation is initiated while the opening device is under operation
The opening and closing times (when indicated) shall be verified
When required by the purchaser, this test is repeated as a type test, for abnormal environmental and/or operating conditions (7.3.1 of EN 50123-1)
Dielectric tests shall be in accordance with 7.5 of EN 50123-1, with the following qualifications
Dielectric tests must be conducted on a new circuit breaker installed under actual service conditions If the circuit breaker's supporting structure is composed of insulating material, metallic components should be added at the fixing points to accurately simulate installation conditions.
This test is a type test only for circuit breakers having U Nm above 2 500 V and is an investigation test in all other cases
The test shall be performed in accordance with the requirements of 7.5.1 of EN 50123-1 both in the open and closed positions
8.3.3.3 Power-frequency voltage withstand test
These tests are routine tests
This test shall be carried out in accordance with 7.5.2 of EN 50123-1 both in the open and closed positions
The test voltage is applied for 60 seconds under specific conditions: a) between all interconnected auxiliary and control circuits, which are not typically linked to the main circuit, and the metallic frame of the circuit breaker; b) if an auxiliary circuit is designed to be physically segregated or completely isolated from other auxiliary circuits, the test is conducted between this isolated circuit and the rest; c) any equipment that has previously passed this test successfully may be disconnected.
NOTE Semiconductors should be short-circuited during the test
R.M.S test values are specified in accordance with Table 1 of EN 50123-1
The test level for contacts can be set slightly below that of the main circuits and earth Additionally, varying voltage levels can be selected for auxiliary and control circuits, both to earth and among themselves.
Repeated tests are carried out at 75 % of the voltage value stipulated for a new circuit breaker submitted for the first time to dielectric tests
General provisions concerning temperature-rise tests are given in 7.4 of EN 50123-1 Temperature-rises specified in clause 6 of EN 50123-1 shall not be exceeded
In cases where mutual heating among the main circuit, control circuit, and auxiliary circuit is significant, it is essential to conduct the temperature tests specified in sections 7.4.3 and 7.4.4 of EN 50123-1 simultaneously.
8.3.5 Verification of the adjustment of the relays and releases
Ensure that the current flowing through the circuit breaker, in the correct direction for unidirectional circuit breakers, triggers the opening within the specified limits outlined in section 6.6.2.2 for each value within the setting range.
For circuit breakers whose operation is affected by the rate of rise of the current, in the vicinity of the setting values, 200 A/s shall not be exceeded
8.3.5.2 Shunt release and undervoltage relay or release
Check that these devices cause opening of the circuit breaker within the limits given in 6.6.2.3 and 6.6.2.4 respectively
This test is a type test and is carried out in laboratory conditions
The test procedure shall follow the requirements of 7.3.2 of EN 50123-1 The number of cycles to be carried out shall be as indicated in 6.5
The test must be conducted on a circuit breaker equipped with its own closing device, energized at its rated voltage U Ne, ensuring that the temperature rises specified in clause 6 of EN 50123-1 are not exceeded during the testing process.
The test is a type test and is carried out in laboratory conditions
The test procedure shall follow the requirements of 7.3.3 of EN 50123-1 The number of cycles to be carried out shall be as indicated in 6.5
The test must be conducted on a circuit breaker with a closing device, supplied at a voltage specified in section 5.2 of EN 50123-1 It is essential to ensure that the temperature rises outlined in clause 6 of EN 50123-1 are not exceeded during the testing process.
All operating cycles for I and R circuit breakers, as well as the initial 4,000 cycles for L circuit breakers, should be performed without maintenance Subsequent cycles for L circuit breakers may include maintenance as per the manufacturer's guidelines, but must not involve any component replacements.
The circuit breaker is considered to have successfully passed the test if it can operate normally afterward, requiring only cleaning and greasing for maintenance, as specified in this subclause.
8.3.8 Verification of the making and breaking capacity in short-circuit conditions and of the H, V or S characteristic
8.3.8.1 Tolerance on the test values
The test is conducted according to the manufacturer's specified values in sections 5.3.1 to 5.3.3, following the guidelines in 5.3.4 It is deemed valid if the reported values fall within the acceptable limits outlined in Table 6 of EN 50123-1.
For laboratory reasons these tolerances may be revised by mutual agreement
The circuit breaker shall be a complete assembly The control device, except for control motors, shall be supplied at its minimum voltage value, as stated in 5.4
The circuit breaker must be tested within an enclosure that meets the manufacturer's specified minimum volume and dimensions, or in open air for cell applications, utilizing metal screens to replicate the proximity of cell walls and ceiling These screens or cubicles should be connected to the earthed frame of the circuit breaker, and may include insulation lining if that reflects the circuit breaker's operational conditions.
The test outlined in section 5.3.4 involves specific duties tailored to a class of circuit breaker, incorporating a suitable duty cycle and release setting Each duty cycle must be executed once, and due to the rigorous nature of the test, maintenance of the circuit breaker is permitted between duty cycles.
Where a circuit breaker can have applications of either of its primary terminals connected to the positive supply, then the test duties f), e) and d) shall be repeated for both connections
After each test duty, a dielectric test is required in accordance with 7.6.3 of
A typical arrangement of the test circuits is shown in Annex A of EN 50123-1
Details of the test circuit are given in 7.6.1 of EN 50123-1
For test duties e and d, if there is inadequate impedance on the load side, the test duty must be repeated by connecting the live wire to the opposite terminal This ensures that both terminals of the circuit breaker are subjected to stress against the earth during the arc interruption process.
For V type circuit breakers, it is essential to conduct the test duty \(d\) with all circuit impedances located on the load side to effectively stress the free wheeling diode This test should then be repeated with all impedances positioned on the supply side to evaluate the performance of the overvoltage absorbing devices.
Test duty e should also be performed in this way if the V type circuit breaker can be located at the maximum energy position
8.3.8.5 Time-constant of the test circuit
For maximum faults, the time constant is assumed to be correct if the peak to steady state ratio is at least 1.42 Additionally, during the maximum energy test duty, the circuit time constant must be no less than 0.5 times the rated track time constant \( T_{Nc} \) (refer to section 5.1.1.3).
General
This annex gives a summary of the information which may be used as guidance to fulfil clause 7.
Procurement specification
When issuing procurement specifications, purchasers should include specific technical requirements for installations, such as service conditions that differ from "normal" as defined in EN 50123-1, details on circuit breaker types and their duties, and the necessary data outlined in clause 5 Additionally, specifications should cover particular features related to clause 6, terminal details, continuous ratings, load cycles, and the test duty cycle (duty 1 or duty 2) It is also essential to specify the calibration range for overcurrent protection, the maximum and minimum voltage for auxiliary supply, and arrangements for transport and delivery, including maximum packing dimensions Lastly, if required, lower mechanical operation cycles for L circuit breakers should be noted as per clause 6.5a.
Manufacturer's specification
The following information should be given by the manufacturer: a) identification
1) name of the manufacturer or trademark;
3) reference to the National Standard corresponding to this European Standard, which the manufacturer declares compliance with;
4) manufacturing year and serial number;
5) marking of all connections (primary and auxiliary) b) characteristics
1) confirmation of the type, use and duties (see 5.2b and c and 5.3.4);
2) suitability to use service requirements differing from normal (as defined as normal in clause 4 of EN 50123-1);
4) range of voltage(s) at which the circuit breaker operates satisfactorily;
5) rated current(s) at the rated voltage(s) of the equipment I Ne;
6) rated track time constant T Nc;
8) circuit breaker test duty cycle;
10) restriction of V to rectifier substation use only, if applicable;
11) maximum arc voltage in test conditions;
12) conventional thermal current and enclosed thermal current, if applicable I th, I the;
15) rated impulse withstand voltage level U Ni, if applicable;
16) power required at rated control voltage to close circuit breaker;
17) power required at rated control voltage for shunt trip coil or equivalent device;
18) confirmation of the suitability to the load cycle specified by the purchaser
19) resistance in the circuit breaker main circuit;
20) guaranteed temperature-rises (see clause 6 of EN 50123-1) at rated service current in the various parts of the circuit breaker and temperature-rises in overload conditions;
21) rated short-circuit making and/or breaking capacities at the various duties specified
22) break time as a function of rate of rise of current (di/dt);
24) cut-off current as a function of rate of rise of current (di/dt);
27) whether the circuit breaker is held closed electrically, magnetically or mechanically;
28) IP code in the case of an enclosed equipment (according to EN 60529);
29) characteristics of the overcurrent protection relay and releases;
30) rated voltage(s) of the control circuit(s), nature (and frequency) of the current(s);
31) nature of the current (rated frequency) and supply voltage of the control, if different from those of the control coil;
32) rated air pressure and pressure variation limits (for devices with pneumatic control);
33) weights of the complete circuit breaker and of the withdrawable part if any;
34) minimum size of the enclosure and, if applicable, data concerning ventilation, to which the rated characteristics apply;
35) minimum distance between the circuit breaker and metal parts connected to earth for circuit breakers which are intended for use without an enclosure;
36) rated voltage of the control circuit of the shunt release and/or undervoltage release (or no-voltage release);
37) rated current of overcurrent releases;
38) setting range(s) of the overcurrent release;
39) method for varying current calibration;
41) effect, if any, of temperature variation on current calibration;
42) type and power consumption of the anti-pumping device;
43) type and power consumption of interposing relays;
44) type and power consumption of all built-in control equipment;
45) number and type of auxiliary contacts and nature of the current, rated frequency (if applicable) and rated voltage(s) of auxiliary switches;
46) continuous rating and breaking capacity of each auxiliary contact;
47) method of fixing the circuit breaker;
48) details of arrangements for manoeuvrability of circuit breaker truck, if any;
49) details of draw-out space required;
50) details of access required at rear;
The manufacturer's recommended routine maintenance period for circuit breakers, including contacts and arc chutes, is determined by the number of operations at the rated service current (INe) and the maximum short-circuit current (INss).
NOTE The above characteristics are only used where they specifically apply to the application c) drawings
The article outlines the general arrangement and sectional elevations of a circuit breaker, detailing its overall dimensions and the necessary space for removing the arc chute It also specifies the required space for insulated and/or earthed components, if applicable, as well as the space needed for circuit breaker withdrawal Additionally, it includes maximum shipping dimensions, shipping weight, estimated gross weights, and considerations for shock loading on floors.
3) general arrangement of any floor irons and area to be left unscreened for the contractor to finish, and loading details;
4) characteristics (i2t or break time or cut-off current) of the circuit breaker;
5) oscillographic records showing circuit breaker performance under the specific interrupting conditions;
6) installation, operation and maintenance manuals.