Two standards that specify requirements for low-voltage circuit-breakers (cbs) have been causing confusion for some time among designers and installers of electrical installations. They are BS EN 60898-1 and BS EN 60947-2 and questions are often asked about the difference between them. However if we perform the calculation using 230Vac will will get a reduced permissible Zs. This would seem to suggest to me that we could be failing Zs values that allow enough current to flow in the event of a fault to trip the fault protective device. Although cbs from different manufacturers may appear similar, the technical performance, dimensions and terminations are not always compatible.

It means at Isc=10kA 2P breaker is much reliable and can withstand up to Icu=20kA than 1P or 1P+N breakers (Icu=10kA). Yes. The rated voltage currently required in industrial use CBs is 400 V, 440 V, 690 volts, or higher values up to 1000 V. Compare those numbers to the usual value 230V/400 V for residential MCBs. Reference ambient temperature is 30°C for households. The same goes for impulse withstand voltage (Uimp), IEC 60898-1 requires 4kV, in line with the use for final circuits. Whereas for industrial circuit breakers, the usual values of Uimp are 6 or 8kV, in line with the position of the circuit breaker at the origin of the installation. higher permissible loop impedance using 240Vac in our calculations as per BS7671:2018 clause 411.4.4 ( Zs × Ia ≤ U0 × Cmin). Any installer who plans to substitute a different cb must obtain authority from the assembly manufacturer to do so in compliance with Regulation 536.4.203. Otherwise, responsibility for the testing and integrity of the compatibility between devices would be down to the contractor. When this is not carried out, there is a probability that, in the event of an accident, fire or other damage, the installer would be accountable under Health and Safety Legislation. You should keep it simple: residential installations – IEC60898-1, industry and commercial buildings – IEC60947-2 &– IEC60898-1.As mentioned in the blog, MCB manufactured as per IEC 60898 to be used in residential buildings or similar applications. In industrial applications can be used breakers certified as per IEC 60947-2 or IEC 60947-2 and 60898 both.

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. Alternatively, the maximum Z s value can calculated using the time- current characteristic of the MCCB being used, as shown in Fig. 2 for a 32 A MCCB. IEC 60898-1:2015 applies to a.c. air-break circuit-breakers for operation at 50 Hz, 60 Hz or 50/60 Hz, having a rated voltage not exceeding 440 V (between phases), a rated current not exceeding 125 A and a rated short-circuit capacity not exceeding 25 000 A. This second edition cancels and replaces the first edition published in 2002, Amendment 1:2002 and Amendment 2:2003. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: 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, We have MCCB NSX 250H with Micrologic 2.2 trip unit installed in our utility station. We would like to connect 440V HPU with star-delta starter, inrush/peak start up current is abt. 448A, FLA is abt. 198A (HPU motor has it’s own overload protection). Is this breaker fit for purpose along with Micrologic 2.2 trip unit? What will be be approximate short-time delay timing for 448A inrush?If I understood your question well, the difference comes from ratio of nominal Icn and ultimate Icu breaking capacities ratio to service breaking capacity Ics. It is usually stated in percentage 100%, 75%, 50% or less. As higher this value as more “robust” breaker to withstand Ics.

As you can see, breaker performs 7,5kA service capacity which is applicable for both standards requirements to declare. But having looked at the fuse curve characteristics in the BS7671 - P199, the Graph straight lines from 0.1s to about 10 seconds,current over 200A will disconnect legally - I just cant understand how 200A and my PSC reading of 767A on the shower circuit will disconnect at the same time (is this white MAGIC or am i missing the point). I know the curve covers 0.4 to 5S But I cs is expressed as a percentage ratio of I cu and gives the maximum short-circuit current a cb can break three times and still function in normal service. However, as the resistance of conductors tends to increase with temperature, the ambient temperature at which testing is carried out is a significant factor in determining the temperature (and therefore the resistance) of conductors. https://blog.se.com/power-management-metering-monitoring-power-quality/2013/07/16/iec-60947-2-the-all-risk-insurance-for-circuit-breakers/Circuit-breakers are primary circuit protective devices. They are not intended for frequent switching of loads. Infrequent switching of cbs on load is admissible for the purposes of isolation or emergency switching. From your article I get that IEC 947-2 has stronger specs more than IEC 898-1 such as ( Ue , Ui , pollution degree) but how Icu for 947 ( stronger conditions ) can be greater than 898 for the same MCB A cb designed for Pollution Level 2 conditions would not be suitable for harsh outdoor or humid applications that require Pollution Level 3.

This standard BS EN 60898-1:2019 Electrical accessories. Circuit-breakers for overcurrent protection for household and similar installations is classified in these ICS categories: Table B6 of the OSG and Table A4 of GN 3 contain maximum Z s values for circuit-breakers based on the cross-sectional area (csa) of the protective conductor and at an assumed conductor temperature of 10°C.Yes it is safe choice. iC60N 2P @230Vac during the trip has a double break effect (circuit is interrupting in 2 places, per each pole).