Non-Tariff Barriers

Non-Tariff Measure

NTM classification

B82: Testing requirement 

Date when the measure came into force

16 December 1987 

Publication where the measure is specified

Government Notice 2286 (Government Gazette 10987) Of 16 October 1987 

Regulation where the measure is specified

Compulsory Specification For Earth Leakage Protection Units 

Country/Region applying the measure

South Africa 

The rationale of the measure

This specification covers earth leakage protection units (circuit-breakers) for use in domestic and industrial or similar electrical installations and connected to a source of alternating current supply operating at a frequency of 50 Hz, the neutral conductor of which is connected to the general mass of earth on the supply side, and subject to the following limitations:
(a) Maximum rated voltage.................................................. . . . . . 500v.
(b) Maximum rated current ....................... ................................ 100 A.
(c) Maximum rated earth leakage tripping current.. ........................30mA
(d) Ambient temperature ..................... ...................................... - 5 ̊C to +10 ̊C.

The earth leakage protection units covered by this specification are intended to reduce fire and electrocution
hazards caused by current leaking from line and neutral conductors to earth.
This specification does not cover earth leakage protection units intended for service under extreme operating
conditions such as continuous high atmospheric humidity, atmospheric pollution, mechanical vibration. mechanical shock, and excessively high or low temperatures. 

Description of the measure

6.2.1 Unless otherwise required, carry out the tests on each EL circuit-breaker as a whole and with the ambient
temperature maintained at 15-25 ͦͦ C.
6.2.2Test each single-pole and switched-neutral EL circuit-breaker, and each single-pole and neutral EL circuit-breaker, as a double-pole EL circuit-breaker.
6.2.3 With the exception of the air-core reactor in any phase (which shall be shunted by a resistance of a value such that the current through the resistor is 0,6 -0,7 % of the current through the air-core reactor), do not connect in parallel the reactance or resistance components of a test circuit load impedance.
Except where otherwise specified, use for the test an alternating current supply of practically sinusoidal wave form and that has a frequency of 50 +- 2 Hz. For any test where no tolerances are stated, the following general tolerances shall apply:
Voltage +- 5%; Current +- 5%; Frequency +- 2Hz; Time +- 5%
6.3 INSULATION RESISTANCE TEST: Measure at a d.c. voltage of 500 V the insulation resistance in the following positions:
(a) Between live terminals and any metal parts that would be exposed when the EL circuit-breaker is mounted in its normal position. Do this test (with all exposed metal parts electrically connected together and with all live terminals electrically connected together) with the EL circuit-breaker first in the "ON" position and then in the "Off" position.
(b) Between each incoming and each outgoing terminal, with the EL circuit-breaker in the "OFF" position
and, in the case of multiple circuit-breakers, with electrical interconnection between -
(1) all incoming terminals, and
(2) all outgoing terminals.
Check for compliance with 4.2.
6.6 OVERCURRENT RELEASE TEST.
6.6.1 Mounting and connections: Mount the EL circuit-breaker as for normal service (with all covers in position) and using conductors of length at least 1 m and of the size given in Table 2, appropriate to the current rating of EL circuit-breaker, connect it to the power supply.
6.6.2 Procedure:
(a) Using any convenient voltage, determine the current time charactersist of the EL circuit-breaker operatinf it at ambient temperature of 25+- 5 ̊C at all the following percentages of rated current:
135 1000
200 2000
400
Test each pole fitted with an overcurrent release separately except that for calibration at 135 %; of the rated current, all poles shall be tested simultaneously and shall be equally loaded. Test two poles. or one pole and the neutral, to ensure that the currents through the sensing device are balanced. Check for compliance with 4.5.1.3
Note: Where the characteristics of an EL circuit-breaker are such that the above points do not produce a
smooth curve. additional intermediate points may be taken as required.
(b) Finally, verify the current rating by operating the EL circuit-breaker at its rated through all poles
simultaneously for at least two hours.
6.7 OVERLOAD TEST FOR A N EL ClRCUIT-BREAKERS FITTED WITH AN OVERCURRENT RELEA SE.
6.7.1 Test circuit: With the EL circuit-breaker mounted as for normal service, connect it into a !circuit in which the current has been adjusted to 600+-5% of the relevant rated value and the applied voltage to 100 +-5% of the rated voltage of the EL circuit-breaker. Use an a.c. circuit having a lagging power factor of 0,45-0.5.
6.7.2 Procedure: Unless otherwise required, close and open the EL circuit-breaker 50 times consecutively at the rate of six operation cycles per minute and unsure that the contacts do not remain closed for more than two seconds in each cycle. In the case of multi-pole EL circuit-breakers, test simultaneously all poles intended to interrupt current, each pole carrying the current specified above. In the case of an EL circuit-breaker with no overcurrent release but fitted with a shunt release, carry out the test as described above but so energize the release (by applying a voltage equal to the rated voltage of the release) that the circuit-breaker opens 20-40 ms after closing. Check for compliance with 4.6.

6.8 OVERLOAD TEST FOR AN EL CIRCUIT-BREAKER NOT FITI'ED WITH AN OVERCURRENT RELEASE.
6.8.1 Test circuit: With the EL circuit-breaker mounted as for normal service, connect it into a circuit in which the current has been adjusted to 150% of the relevant rated value with a power factor of 0,95 and the applied voltage has been adjusted to 110+- 5 % of the rated voltage of the EL circuit-breaker.
Procedure: Close and open the EL circuit-breaker five times consecutively and ensure that the contacts do not remain closed for more than two seconds in each cycle. In the case of multiple EL circuit-breakers, test simultaneously all poles intended to interrupt current, each pole carrying the current specified above. Check for compliance with 4.6.
6.9 TEMPERATURE RISE TEST: Mount the EL circuit-breaker as for normal service (with all covers in position) in a place where there are no draughts and where the ambient air temperature is 25 +- 5 ̊C.
Using conductors each of length at least 1 m and of the size given in Table 2, appropriate to the current rating of the EL circuit-breaker, connect the EL circuit-breaker to the power supply and pass the rated current through the EL circuitbreaker for a period of two hours or until thermal equilibrium is attained. Then measure the relevant temperatures (see Table 4)by means of thermocouplesor any other acceptable method, at the points where the temperatures are judged to be highest. Check for compliance with 4.7.
6.10 MECHANICAL STRENGTH TEST.
6.10.1 Apparatus:
(a) A mechanical strength test apparatus as shown in Fig. 1. The metal cylinder A of mass 250 g and of
external diameter 25 mm fits loosely over the guide rod B. The guide rod is not rigidly fixed to the frame of the test apparatus and can be easily slid up and down. A hard fibre washer C ofdiameter25 mm and of thickness 12.5 mm is fixed to the bottom of the guide rod.
6.10.2 Specimen: Use one EL circuit-breaker from the sample.
6.10.3 Procedure:
(a) Place the hardwood block on the base of the test apparatus and f m l y hold or otherwise mount the
specimen on the block with its mounting surface down (i.e. toggle uppermost).
(b) Raise the guide rod and so move the block that, when the guide rod is lowered, the fibre washer rests on the surface of the specimen. Lower the guide rod, raise the metal cylinder to a height of 250 mm above the fibre washer, and allow the cylinder to drop onto the fibre washer.
(c) Repeat the drop twice, ensuring that the toggle is subjected to one drop when it is in the OFF position.
(d) So turn the specimen that it lies on its side on the block and proceed as described in (b) above, subjecting the specimen to three drops, two at random (but not on an edge of the specimen) and one approximately in the middle of the terminal guard.
(b)A rectangular hardwood block D that fits on the base of the test apparatus.
(e) Turn the specimen onto the other side and repeat the procedure given in (d) above.
(f)After the specimen has been subjected to nine drops, examine it for compliance with 4.8.
6.11 TEST FOR PERFORMANCE OF AN EL CIRCUIT-BREAKER UNDER EARTH FAULT CONDlTIONS:
Connect a 1 A fuse between the earthed conductor of the supply circuit and any metal parts that will be exposed when the EL circuit-breaker is mounted in its normal position. Connect all exposed metal parts together electrically. Connect the EL circuit-breaker to a power supply having an open circuit voltage of 100 2 5 % of the rated voltage.
Adjust the impedance of the load to provide a prospective earth fault current of 500 A with a power factor of 0,45-0,50. Cover that part of the surface of the EL circuit-breaker in which the toggle is situated with clean dry butter muslin that complies with requirement for Grade 1 butter muslin of SABS 446 'Absorbent gauze (fabric and swabs) and butter muslin'. Ensure that any cut or torn edges of the muslin are not exposed directly to the arc openings where flame may be emitted. Apply the earth fault current once by means of a separate switch in the supply circuit and once by means of the EL circuit-breaker switch, with the separate switch closed (i.e. close the EL circuit-breaker switch onto the fault.) In the case of a three-phase EL circuit-breaker test only one pole. Check for compliance with 4.9.
Immediately after the test, check the EL circuit-breaker for performance under earth leakage conditions at room temperature, the earth leakage current being applied gradually (see 6.14.3). Should the unit fail to comply with the requirement given in 4.12 (d), repeat the earth leakage test (as in 6.14.3) after 24 hours. 

Reference of the measure

Regulation 6.2.1 - 6.11 

Measure also domestic

Yes 

Products affected by the measure.

Description

Earth leakage protection units (circuit-breakers) 

Countries/Regions affected by the measure.

Description

All countries