IB 6.1.2.8-1B
Page 3
ABB
INTRODUCTION
The electronic trip control unit described in this publication is a solid state,
microprocessor controlled unit, used in conjunction with a power circuit breaker to
protect power systems. The power circuits being protected are typically 3-phase,
with and without a neutral connection, 50 or 60 Hz with AC RMS voltages between
208 and 600 volts and continuous currents as high as 4200 amps, while ground
currents may not exceed 1200 amps.
The primary function of the electronic trip control unit is the coordination in the
opening of circuit breakers to protect equipment in the event of a fault that
produces short circuit currents of up to 130 KA.
The MPS-C 2000 trip control unit measures current to an accuracy of within 1% of
the cicuit breaker rating.
The Voltage Interface Module (VIM) option measures voltage to an accuracy of
within 1% of the circuit breaker rating, and power to within 2% of the circuit
breaker rating.
The trip unit is completely self-powered, taking the the tripping energy from the
current through the breaker without any auxiliary power supply.
The complete control of the circuit breaker is achieved by a system comprising:
(a) current sensors, (b) an electronic trip control unit, and (c) a magnetic latch trip
device.
The sensors, the electronic trip control device and magnetic latch are mounted
as an integral part of the circuit breaker to provide complete protection for
overcurrent, short circuit and ground faults. Internal diagnostic circuitry is provided
to determine and visually identify the cause of circuit breaker tripping, either as
overload, short circuit or ground fault.
