IEC 62271-1 requires switchgear to pass electromagnetic compatibility tests: main circuit emission (RIV, only from 245 kV and if the product standard asks for it), radiated emission of the control electronics, and immunity to fast transients and oscillatory waves. They apply only to auxiliary and control circuits with electronics.
Short answer
In a substation, the circuit breaker generates disturbances when it operates and at the same time depends on control circuits with relays, controllers and electronic power supplies that must keep working. IEC 62271-1 (2017 edition) covers both directions: it requires switchgear to pass the electromagnetic compatibility (EMC) tests of clause 7.9 (clause 6.19), with emission from the main circuit, emission from the auxiliary and control circuits, and immunity of the latter.
Main circuit emission: RIV
The radio interference voltage (RIV) test applies only to switchgear of 245 kV or more and when the product standard specifies it (clauses 7.3 and 7.9.1.1). The standard justifies this with service experience: below 245 kV, radio interference effects are negligible.
In the test, the voltage is applied between the terminals and the earthed frame, with the equipment closed. With the equipment open, it is applied between one terminal and the others connected to the frame. The equipment is tested with all the accessories that can influence it, such as grading capacitors, corona rings and high-voltage connectors.
Emission from auxiliary and control circuits
If the auxiliary and control circuits include electronic equipment or components, they are tested for emission. If not, no test is required (clause 7.9.1.2). The electronics must meet the radiated emission requirements of CISPR 11:2015 for group 1, class A equipment. A measuring distance of 10 m can be used instead of 30 m if the limits are raised by 10 dB.
The standard gives precedence to its EMC requirements over other specifications for these circuits. The test is made on a representative auxiliary and control circuit, because individual components are tested to their own standards.
Immunity of auxiliary and control circuits
Clause 7.9.2 applies if the circuit includes electronics. A typical circuit is tested, complete or by subassemblies (the central control cabinet, the mechanism cabinet, a measuring or monitoring system). The test voltage is applied at the interface of the circuit or subassembly under test.
The two specified immunity tests simulate two different origins:
| Test | Standard | What it simulates |
|---|---|---|
| Electrical fast transient/burst | IEC 61000-4-4, 5 kHz repetition | Switching in the auxiliary and control circuit itself |
| Damped oscillatory wave | IEC 61000-4-18, at 100 kHz and 1 MHz (tolerance ±30%), common and differential mode | Switching in the main circuit |
The power, signal and earth ports of the cabinet are chosen per IEC 61000-6-2. Signal ports include control, communication (for example, data buses) and measurement lines, such as those of CTs and VTs.
What must keep working
Per clause 7.9.2.4, the circuits must withstand each test without permanent damage and afterwards be fully operational. A temporary loss of functions is allowed according to the criteria of Table 18:
- Criterion A: normal operation within the specification limits. It applies, among others, to protection and teleprotection and to control and command.
- Criterion B: temporary degradation or loss of a function, which recovers by itself. It applies, for example, to alarm.
On-line processing, monitoring and self-diagnostic functions that form part of the control circuits must meet criterion A.
Additional tests with DC supply
Clause 7.9.3 seeks to qualify the complete assembly without repeating the test of each component:
- Ripple on the DC power supply port (IEC 61000-4-17:2009): level 2, with a ripple frequency equal to three times the rated frequency. Criterion A.
- Voltage dips, short interruptions and variations: per IEC 61000-4-11 for AC supply and IEC 61000-4-29 for DC.
Other tests on auxiliary circuits
In addition to EMC tests, clause 7.10 adds functional tests, tests of auxiliary contacts (rated continuous current, short-time withstand current and breaking capacity), environmental tests (cold, dry heat, cyclic damp heat and vibration) and dielectric tests. Components that meet their own IEC standards and rated values do not need to repeat the test.
Why wiring matters
The tested immunity is valid for the circuit as it was tested. Clause 7.9.2.1 recommends testing subassemblies separately when there are long interconnections or significant interference voltages are expected between them, and makes it mandatory for each interchangeable subassembly. Annex J.5 allows a subassembly to be relocated without invalidating the type test only if the total length of cabling and the number of wires connecting it to the circuit are not greater than in the tested system.
A control cable run with more length or more conductors than the tested system falls outside what Annex J.5 allows without repeating the test.
- Does the auxiliary and control circuit include electronics?
- No: No emission or immunity tests are required
- Yes: Is the switchgear 245 kV or more and does the product standard require RIV?
- Yes: Radiated emission (CISPR 11), immunity (burst and oscillatory wave) and main circuit RIV
- No: Radiated emission (CISPR 11) and immunity (burst and oscillatory wave)
The circuit breaker command arrives through the control cabinet, and its signals pass through the circuit breaker auxiliary contacts. The type tests that include this test are summarized in type tests of switchgear. The digital interface of switchgear describes the other signal path to the circuit breaker.
The other parts of IEC 62271 are organized in the standards for primary equipment testing.
What not to do
- Do not require RIV for a medium-voltage switchgear assembly: the test is for 245 kV or more.
- Do not take cabling different from the tested one as covered: longer or with more wires falls outside what Annex J.5 allows.
- Do not swap an interchangeable subassembly for another without verifying that the most complete applicable one was tested and that the manufacturer’s design rules are followed.
- Do not accept a loss of protection function during a transient: the required criterion is A.
When to call us
At Tiza Group we configure, test and integrate the bay controllers, protection and communications of your switchgear, and review the control cabling. See our control, protection and communications service. Write to us and we will quote it.
Related guides
- Type tests of switchgear: what is tested
- Digital interface of switchgear (IEC 62271-3)
- Electromagnetic compatibility in instrument transformers
- Electromagnetic immunity of a low-power instrument transformer (LPIT)
- Circuit breaker control cabinet: parts and functions
References
- IEC 62271-1, High-voltage switchgear and controlgear - Part 1: Common specifications for alternating current switchgear and controlgear, 2017 edition: clauses 6.19, 7.3, 7.9.1 to 7.9.3 and Annex J.5.
- CISPR 11:2015, IEC 61000-4-4, IEC 61000-4-17, IEC 61000-4-18, IEC 61000-4-11, IEC 61000-4-29 and IEC 61000-6-2 (cited by the standard).
Frequently asked questions
Which immunity tests does IEC 62271-1 require for control circuits?
Two main ones: electrical fast transient/burst (IEC 61000-4-4, 5 kHz repetition), which simulates switching in the auxiliary and control circuit, and damped oscillatory waves (IEC 61000-4-18, at 100 kHz and 1 MHz), which simulate switching in the main circuit (clause 7.9.2).
At what voltage does the radio interference voltage (RIV) test apply?
Only to switchgear of 245 kV or more, and when the product standard specifies it. The standard states that experience shows radio interference effects are negligible below 245 kV (clauses 7.3 and 7.9.1.1).
Are control circuits tested if they have no electronics?
No. Clauses 7.9.1.2 and 7.9.2.1 state that auxiliary and control circuits are tested if they include electronic equipment or components; in other cases no tests are required.