DSH 644 Simplified test procedure between different poles devices: 1P+N and 2P d
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Simplified test procedure between different poles devices: 1P+N and 2P devices
Table 10
60947-2(ed.3)
Standard:
IEC 60947-2, 3rd edition, 2003
Sub clause(s):
Table 10
DSH:
644
Subject:
Simplified test procedure between different poles devices: 1P+N and 2P devices
Key words:
Tests on 1P+N and 2P devices
Approved by the 45th CTL Plenary meeting 2008
Question:
Considering a case where, within a series of circuit breakers, the two pole version and the 1P+N version have identical construction (neutral pole is a fully protected pole and is identical to a phase pole) and the two pole version and the 1pole+N version have the same voltage rating:
Is it acceptable that the tests performed on the two pole version cover the 1P+N version?
Rationale:
􀂉 According to item 2.3.1 of IEC 60947-1 (2004-03), there is no difference between one pole plus neutral and two pole devices, provided that the neutral pole is technically identical to the phase poles.
2.3.1 pole of a switching device:
portion of a switching device associated exclusively with one electrically separated conducting path of its main circuit and excluding those portions which provide a means for mounting and operating all poles together
NOTE A switching device is called single-pole if it has only one pole. If it has more than one pole, it may be called multi-pole (two-pole, three-pole, etc.) provided the poles are or can be coupled in such a manner as to operate together.
􀂉 In addition there are some specific requirements, related to markings as describe in item 7.1.8, which are fully satisfied by construction.
7.1.8 Additional requirements for equipment provided with a neutral pole:
􀂃 When an equipment is provided with a pole intended only for connecting the neutral, this pole shall be clearly identified to that effect by the letter N (see 7.1.7.4).
􀂃 A switched neutral pole shall break not before and shall make not after the other poles.
􀂃 If a pole having an appropriate short-circuit breaking and making capacity (see 2.5.14 and 2.5.15) is used as a neutral pole, then all poles, including the neutral pole, may operate substantially together.
NOTE The neutral pole may be fitted with an over-current release.
For equipment having a value of conventional thermal current (free air or enclosed, see 4.3.2.1 and 4.3.2.2) not exceeding 63 A, this value shall be identical for all poles.
􀂉 Concerning the test conditions, the test circuit used for 2 pole circuit breakers (2P or 1P+N) is given in figure 4 of the standard (see page 3).
Based on note 2, the only difference between 2P and 1P+N is the way of connecting the safety area.
For 1P+N, it shall be connected to phase and for 2P it shall be connected to Neutral.
For breaking aspect, it was decided to perform the tests on 2 poles CB for voltages up to 440V covering the case of 1P+N at 240V.
For the clearance to safety area aspect, the voltage between one phase and safety area is maximum in case of 1P +N and equal to 240V maximum. Nevertheless this case is covered by the three phase test performed at 440V, considering that in such case the voltage between safety area and the first pole to clear can reach (1,5x 440V) / (1,732) = 380 V (which is much greater than the 240V of the 1P+N).
Therefore, we can consider that the tests performed on 2P devices, cover 1P+N devices.
Decision:
Yes it is acceptable to cover the 1 P+N version by the tests performed on the two pole version.
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