Circuit & System Protection


Electrical protection equipment range

21 January 2009 Circuit & System Protection

Legrand’s range of electrical protection equipment includes modular MCBs, MCCBs, trip-free switches, earth leakage modules and specially designed accessories like control, signalling and motor operator units.

DIN-rail mounting thermal magnetic DX MCB 6 kA units have capacities up to 63 A and thermal magnetic 10 kA MCBs have capacities up to 125 A. They are available in single, double, 3 and 4-pole variants. Signalling auxiliaries for these MCBs enable auxiliary and fault signalling changeover, indicating the position of the switch and the tripping of the MCB at a fault. Command auxiliaries enable the MCB to be tripped from a remote location.

DPX MCCBs are equipped with thermal magnetic or electronic releases to meet the requirements of demanding installations. These MCCBs are available in six frame sizes with capacities of 125 A to 1600 A units up to 100 kA. All MCCBs have settable adjustments to suit the tripping requirements of the installation. Charts for association and discrimination between MCCBs and MCCBs are available, as well as between MCCBs and MCBs.

Control and signalling auxiliaries include fault signals that indicate the state of the contacts or the opening of the MCCB on a fault. Shunt trips and under-voltage releases allow the remote tripping of a DPX. An 800 ms time-lag for under-voltage releases also prevents false tripping in the event of AC supply micro breaks or micro control. These auxiliaries are common to all frame sizes.

New motors for DPX 125 to DPX 1 600 are designed for remote making and breaking of a DPX circuit and automatically reset in the event of a trip on a fault. A lock prevents operation when working on the line.

An electronic test unit is used to check the operating characteristics of an electronic MCCB. Functions include identification of under-voltage release, monitoring of trip curves, measurement of internal temperatures of the device and memorisation of the number of occasions the device has tripped on a fault since installation.

Residual current relays and separate coils offer residual current protection on large diameter conductors to DPX MCCBs. It is advisable to fit a shunt trip or under-voltage release to the MCCBs or the switches used with them. The smaller frame sizes up to 250 A DPX circuit breakers can be DIN-rail mounted under modular or special faceplates.

For more information contact Legrand, 27 (0)11 444 7971, [email protected], www.legrand.co.za





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