WiPro Event Presentation

Report
IEC 62271-100
Short-circuit current making and breaking tests
Taiwan-European HVAC apparatuses
Accreditation and Certification forum
Harethe El Ouadhane
IEC Expert: Member of MT14 of IEC62271-200
Testing, design & calculation / MVSG & MVCB
Expert for internal arc, making, breaking and STC
Content
1.
Requirements of IEC 62271-100
2.
Basic short-circuit test duties
3.
Single-phase fault tests
4.
Double-earth fault tests
5.
Technology of vacuum interrupters
6.
Extension of the validity of test results and derivations
7.
Conclusion
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1. Requirements of IEC 62271-100
 Mandatory Test
Circuit-breakers shall be capable of making and breaking all short-circuit
currents, symmetrical and asymmetrical, up to and including the rated shortcircuit breaking currents:
This is demonstrated, when the circuit-breakers make and break the specified
three-phase symmetrical and asymmetrical currents between 10% (T10) and
100% (T100) of the rated short-circuit breaking current at rated voltage.
 In addition
Circuit-breakers shall be capable of clearing single-phase short-circuit
currents which may occur in two different cases:
– in effectively earthed neutral systems in case of single-phase faults or,
– in non-effectively earthed neutral systems in case of double earth faults,
i.e. earth faults on two different phases, one of which occurs on one side of
the circuit-breaker and the other one on the other side.
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2. Basic short-circuit test duties
 Number of test specimen
a unique test specimen should be used. Where required, maintenance is
allowed and should be performed as permitted, between each individual testduty in the case of short-circuit tests
The manufacturer shall provide a statement to the testing laboratory of those
parts that may be renewed during the tests.
 No-load test
Before commencing making and breaking tests, no-load operations and noload operating sequences (O, CO and O – t – CO) shall be made and details
of the operating characteristics of the circuit-breaker recorded. Details such as
closing time and opening time shall be recorded.
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2. Basic short-circuit test duties
 Behavior of circuit-breaker during tests
During making and breaking tests, the circuit-breaker shall not
– show signs of distress;
– show harmful interaction between poles and to earth;
– show harmful interaction with adjacent laboratory equipment;
– exhibit behavior which could endanger an operator.
NSDDs may occur during the recovery voltage period following a breaking
operation
 Condition after a short-circuit test-duty
After each short-circuit test-duty, the circuit-breaker shall be capable of
making and breaking its rated normal current at the rated voltage, although its
short-circuit making and breaking performance may be impaired.
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2. Basic short-circuit test duties
 Frequency
Circuit-breakers shall be tested at rated frequency with a tolerance of ±8 %.
However, for convenience of testing, some deviations from the above
tolerance are allowable; for example, when circuit-breakers rated at 50 Hz are
tested at 60 Hz and vice versa, care should be exercised in the interpretation
of the results, taking into account all significant facts such as the type of the
circuit-breaker and the type of test performed.
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2. Basic short-circuit test duties
There are several requirements for the test circuit, test parameters and CB
arrangements in order to simulate the possible worst case switching of the
CB in real system.
In general, closing against the highest making current, opening with
various arcing times and recovery voltages, under the unfavourable
mechanical operating conditions.
The main ones are among others related to:
 Operating sequence O – CO – CO, with or without auto-reclosing
T10, T30, T60, T100s & only O for T100a, SPF & DEF
 Factors for recovery voltages; first-pole-to-clear (neutral earthing) and
amplitude factor (based on CIGRE), RRRV
 Arcing time and arcing window: Depending on the point of mechanical contact
separation, interruption with minimum, medium and maximum arcing time
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2. Basic short-circuit test duties
Schneider Electric – IEC 62271-100: Chapter 6 Type tests
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2. Basic short-circuit test duties
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3. Single-phase tests
Mandatory in effectively earth neutral systems.
The main requirements for the test duty are related to:
 Breaking of the rated symmetrical short-circuit current with the maximum
arcing time and with the recovery voltage based on phase-to-earth voltage
 Outer pole under test to simulate the maximum stress in the coupling
mechanism
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4. Double-earth fault
Mandatory in non-effectively earth neutral systems.
The main requirements for the test duty are related to:
 Breaking of the 87% of the rated symmetrical short-circuit current with the
maximum arcing time and with the recovery voltage based on phase-to-phase
voltage
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5. Technology of Vacuum Interrupters
History:
 1896: First analysis of electrical field breakdown in vacuum (theoretical 6MV
per 1mm)
 1930: Quantum mechanics describes the field emission in vacuum
 1960: First commercial VI in the market
 2012: Over 75% all MV CB uses VI to switch the current
VIs are currently commercially available up to 145kV. Prototypes of multiple
switching units at 220kV or higher voltages are under development.
Development of VIs is continuing towards higher voltages and higher short-circuit
currents with the employment of advanced arc control systems.
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5. Technology of Vacuum Interrupters
Main feature of VI technology:
 High number of operations: Up to 100 of rated short-circuit interruptions and
up to 10.000 of rated current interruptions without any maintenance
 Compact & Lightweight and High Reliability with extremely low failure rate
 Contact materials with low welding tendency and low chopping current
 Contact design with arc control for high interrupting capacity and for
withstanding fast recovery voltages
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6. Extension of the validity of test results
 Who?
- Manufacturer Experts / Expert teams
- Third party Experts
 What?
- Yes it can be extended / it may be extended
- No, it can not be extended
 Responsibility
only manufacturer
 Is not the task of test labs or accreditation institutes
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7. Conclusion
The design and technology of high-voltage circuit-breakers is continuously
developing and will continue also in the future.
Type tests qualify the type of product series while the routine tests ensure that
the manufactured series are always in accordance with the type tested sample
Circuit-breakers qualified according to the IEC 62271-100 are best suited for
switching of short-circuit currents. They are able to switch currents with high
asymmetry and fast rising TRVs without any maintenance throughout the lifetime
Most of the failures are due to inappropriate human behaviors either during the
project management phase (wrong product definition) or during operations
(installation, operation, maintenance, etc.)
Thus, considering additional regulation should not bring more safety.
On the other side deregulating a proven standard will reduce the safety level
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