Application description

The Cutler-Hammer MP-4000 motor protection

relay by Eaton Corporation is a multifunctional

microprocessor-based protective relay for the

protection of three-phase AC motors. The

MP-4000 motor relay may be applied to any size

motor at any voltage level. It is most commonly

used on large, medium voltage three-phase induc

tion motors. It has also been widely used on

important low voltage (480V) motor applications

and synchronous motors.

The MP-4000 motor relay monitors three-phase

and ground currents and three-phase voltages.

It provides motor overload, stall, short circuit,

phase unbalance, single phasing over/undervolt

age, underpower, power factor, and ground fault

motor protection.

It can also be used to provide protection for a load

jam or loss of load condition.

The MP-4000 motor relay provides start control

logic to protect the motor against excessive starts

or starting the motor before it has had sufficient

time to cool down. The MP-4000 motor relay

may be applied to either across-the-line starters

or reduced-voltage starters. On reduced-voltage

starters, the MP-4000 relay can control the switch

from reduced voltage to full voltage based on time

and/or motor transition. The MP-4000 can protect

the starter against failure to transition to full volt

age through contact feedback and an incomplete

sequence function.