Compact® NSF and NSJ 150 to 600 A Circuit Breakers

Section 13—Supplementary Technical Information

IEC 947-2 TEST PROCEDURE

Standard Tests Consisting of seven parts, the IEC 947 Standard applies to all low-voltage equipment designed for industrial application.

Three documents are to be consulted for circuit breakers and switches:

IEC 947-1: general regulations

IEC 947-2: circuit breakers

IEC 947-3: switches

Two Categories of Devices

Breaking Capacity

The IEC 947-1 standard defines two categories of devices:

Category A—devices not specifically designed to carry out chronometric selectivity

Category B—devices specifically designed to carry out chronometric selectivity; these circuit breakers possess a compulsory additional characteristic: short-time withstand (Icw)

Ultimate Breaking

Icu is the value to be taken into account when calculating an installation. The rule remains: Icu > Icc

Capacity: Icu

(maximum fault current of the installation).

Breaking

This characteristic indicates the ability of the device to eliminate short-circuit currents less than Icc and

Performance During

with a greater likelihood of occurring, generally near the application. Ics is expressed in % of Icu (values

Operation: Ics

retained by the standard IEC 25-50-75-100% of Icu). This test sequence designed to check the Ics

 

performance, groups together on the same device, following the breaking test (O-CO-CO, see page

 

72), certain checks such as:

 

Temperature rise under In

 

Calibration at 1.45 In

 

Leakage current (for devices suitable for disconnection)

 

The leakage current should not exceed 2 mA under the application voltage (0.5 mA when new). These

 

checks ensure that the device is able to carry out all its functions after elimination of a fault of Ics value

 

and to be put back in operation; hence the notion of breaking power performance during operation Ics.

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Schneider Electric Class 615 dimensions IEC 947-2 Test Procedure, Two Categories of Devices Breaking Capacity