Square D KQ B 32 AMP MCB 240 v BS60898 10B132 A 10Ka CIRCUIT BREAKER

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Typically IEC 60898-1 certified circuit breakers meet required performance to prove proper protection of household installations: Pollution degree 2, impulse voltage 4kV, isolation voltage is the same as nominal voltage 400V. Also, the requirements of this standard are adapted for non-technical users which is why limited technical information is printed in detail on CBs. I work for the utility in South Africa and am researching the use of MCB’s at the PUC between the utility and an IPP. I would agree with Mr Johnson. I would also suggest that if your U0 is not subject to the +10% tolerance then disconnection times as per Table 41.1 can be lifted from the 230v column.

I am being told by an inspector that we have to use 230Vac when performing permissible earth loop impedance calculations as per BS7671:2018 clause 411.4.4 Zs × Ia ≤ U0 × Cmin.Where manufacturers’ values of Z s for MCBs are used, they will often recommend multiplying the measured value of Z s by a correction factor, to correct for ambient temperature. For example, Schneider, recommend using a factor of 0.8,

Circuit-breakers to BS EN 60898-1 can also comply with BS EN 60947-2 but the short-circuit breaking capacity of each may be different. Some manufacturers state that their cbs with a short-circuit capacity of say, 10 kA comply with BS EN 60898-1 and the same cb with a short-circuit capacity of 15 kA complies with BS EN 60947-2.

How comes BS 88 and bs1361 fuses have two tables for 0.4s and 5S but 60898 fuses have one which covers both. Many ABB fuses require more tripping current (Ia) to operate in 0.2 seconds compared to a 0.4 second trip. It is higher because of lower Icu breaking capacity ratio to service breaking capacity Ics, eg. 75% instead of 100%. In any case it will break 15kA.