Softstart UK

MPC-6

MPC-6 Motor Protection & Control Relay

The MPC-6 Motor Protection & Control Relay is a new generation of microprocessor based device designed to protect & control three phase induction motors.

The MPC-6 incorporates three main functions.

Motor protection.
Supervision and communication.
Motor Control.

Motor Protection

AC motors are very rugged and reliable when operating within their limits. However, they are usually designed to operate close to their rated limits with minimal margins for operating under abnormal conditions.

A comprehensive protection device is required to accurately create a "Thermal Model" so that the motor can run safely within its limits. This device should protect the motor from abnormal conditions in the power supply, motor and cable faults, as well as operator errors.

The MPC-6 monitors one voltage and three phase currents (true RMS line currents are measured at a sampling rate of 0.5 ms). The MPC-6 calculates the true RMS ground fault current by summing up the three phase currents. For small motors, if only ground fault is to be measured, it is possible to connect it to "I1". The MPC-6 monitors a single temperature (RTD or PTC/NTC Thermistor) input. Overall, the MPC-6 provides a comprehensive protection and control package.

Protection Types

Maximum start time,
Too many starts
Under-current
Load increase
Over-current Jam / Stall
Over-current Short circuit
Thermal level (Overload) Alarm
Thermal level (Overload) Trip
Unbalance current
Phase Sequence
Ground fault current
Under-voltage
Over-voltage
Wrong Contactor Status
Comm. Port Failure
External fault 1 - N.O./N.C contacts
External fault 2 - N.O./N.C contacts
Over Temp. Level 1&2 (using PT100 or PTC/NTC Thermistor)

Individual Protection settings

Protection levels and time delay settings are individually configured through the keypad on the front panel or through the communications port.

Configurable operation

Unique Tripping/Alarm options make it possible to designate any of the above faults as an Alarm, Trip, both or none. Furthermore, two auxiliary relays can be designated to operate with any of the supported faults.

"Time to Trip" & "Time to Start"

When current exceeds the overload setting a built-in unique algorithm calculates the point in time at which the motor will be tripped (when thermal capacity reaches 100%). This feature enables the operator or host computer to take corrective actions before the actual trip occurs. After the MPC-6 has tripped the motor, the MPC-6 calculates the time delay after which the motor can be restarted, once it has cooled down.

Informative data

Data is display on an illuminated LCD (Liquid Crystal Display) with two (2) lines and sixteen (16) characters each providing clear status and statistical information. The same information is available via the serial link.

Actual Data

Voltage, Phase currents, Ground fault current, PT100 / Thermistor Temp. / resistance, Motor load in % of FLC, Thermal Capacity, Time to trip, Time to start, Unbalance current.

Statistical Data

Motor's running hours
Total number of starts
Total number of trips
Last start time
Last start current peak
Last Trip
Last Alarm
Pre-Trip Phase current and Ground fault current.

Serial Link Communication

RS485 serial link with MODBUS communication protocol, operating at a baud rate of 1200 up to 19200 bps enables monitoring of set points and actual parameters. Modifying the set point parameters through the serial link makes it very easy to enter user set points in place of factory default parameters. The serial link also enables remote control of the motor. Up to 32 MPC-6 devices can be connected on the same link to the host computer. When the need for more than 32 devices arises, it is possible to use the MMI & Data highway equipment for an unlimited number of devices to be connected to the host computer.

Easy setting and operation

The front panel LCD together with a keypad and LEDs provides a user friendly interface, accurate digital parameters setting, actual parameters reading, and detailed trip and alarm messages display. Unauthorized setting changes can easily be prevented by the MPR-6 software.

Hardwired Motor Control

Inputs 1 & 2 are incorporated to enable two common control modes:
1. Start and Stop push-buttons.
2. Start / Stop toggle switch.

Serial Link Motor Control

The MPC-6 communication, allows for remote control of the motor through the serial link.

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