Eaton MP-3000 Motor Protection Relay Guide

Program button: Enter programming mode

Emergency Override button: Reset to start blocking in emergency situations

Mode button: Four mode selection buttons

Monitor: Monitoring mode, displaying real-time data

View Setting: View Setting Mode

History: History mode

Log: Log mode

Navigation buttons: Six buttons with up and down arrows used to navigate between pages, rows, and values.

Help button: Provides scrolling explanations of the current displayed content, including unit information.

Reset button: Reset the trip status and exit the current mode.

3.2 LED indicator lights

There are a total of 10 LED indicator lights on the panel:

LED function

Protection mode indication

Program programming mode indication

Trip trip event indication

Alarm alarm relay activated

Aux 1 auxiliary relay 1 activated

Aux 2 auxiliary relay 2 activated

Monitor monitoring mode activated

View Setting View Setting Mode Activation

History mode activation

Log mode activation

3.3 Default Mode Display

In motor status or default mode, display the basic status of the motor and relay:

Display description

READY-3 motor stopped, 3-phase protection mode ready

READY-1 Warning: Relay set to single-phase test mode

RUN motor is running

START motor is starting

DISARMED Warning: Relay disarmed, unable to trip

ABKSP XX anti reversal activation, XX is the remaining minutes

3.4 Monitoring Mode

Monitoring mode displays real-time data, including:

MONT I page (phasor measurement)

IAMG: A-phase current amplitude

IBMG: B-phase current amplitude

ICMG: C-phase current amplitude

IXMG: Ground current amplitude

IAAG, IBAG, ICAG, IXAG: phase angle of each phase current

MONT ISO page (sequential component measurement)

11MG: Positive sequence current amplitude

12MG: Negative sequence current amplitude

310MG: Zero sequence current amplitude

11AG, 12AG, 10AG: phase angles of each sequence component

3.5 Historical Mode

Historical mode records key statistical data of motor operation:

HIST MTR (Motor Statistics)

OCNT: The number of startups since the last reset

RT: Accumulated running time

IMS: Maximum starting current

IMR: Maximum operating current

UBM: Maximum phase imbalance

WMX: Maximum winding temperature

HIST TRP (Trip Event Statistics)

GF T: Ground fault tripping frequency

I2T T: Number of thermal overload trips

IOC T: Number of instantaneous overcurrent trips

JAM T: Number of locked rotor trips

UL T: Number of underload trips

UB T: Number of unbalanced phase trips

HIST ALM (Alarm Event Statistics)

GF A: Ground fault alarm frequency

I2T A: Number of thermal overload alarms

JAM A: Number of locked rotor alarms

UL A: Number of underload alarms

UB A: Number of phase imbalance alarms

HIST TOT (cumulative statistics)

TRPS: Total number of trips

TRT: Total running time

TOC: Total number of operations

Chapter 4 Protection Principle and Thermal Model

4.1 Current Sampling and Calculation

The MP-3000 samples the input current signal 36 times per power cycle and stores it in the microprocessor memory after digitization. Based on these sampled values, the relay calculates:

RMS current value

Average current value

Phasor calculation, precise measurement of positive and negative sequence currents

The combination of high sampling rate and patented sampling offset technology enables the MP-3000 to accurately measure and account for the impact of harmonics on motor heating.

4.2 Effects of Negative Sequence Current

Any unbalanced three-phase current or voltage can be decomposed into positive sequence, negative sequence, and zero sequence components through mathematical transformations. In motors without neutral line circuits, zero sequence current only occurs during ground faults, so the focus of protection is on positive and negative sequence components.

Negative sequence current generates reverse torque in the rotor, opposite to the main rotation direction of the motor. This reverse work is completely converted into heat, so the negative sequence current has a much greater impact on rotor heating than the balanced positive sequence current.

In the thermal model of MP-3000, the formula for calculating the effective heating current is:

Effective heating current=positive sequence current+K × negative sequence current

Among them, K is the negative sequence emphasis coefficient, reflecting the significant impact of negative sequence current on rotor heating.

4.3 Thermal Accumulator Model

The MP-3000 uses a thermal accumulator (or "hot bucket") model to track the thermal state of the motor:

Hot bucket capacity: calculated based on motor nameplate data (FLA, LRC, LRT, UTC)

Filling process: When the effective heating current exceeds the final trip current (UTC), the hot tub begins to fill

Cooling process: When the current is below UTC, the hot tub gradually drains

Only when the effective heating current is higher than UTC, will the hot tub be filled in the direction of tripping. When the hot bucket is filled to 100%, the relay triggers an I ² t thermal overload trip.

4.4 Alarm threshold setting

The I ² t alarm (I2TA, P4L2) is used to alert operators before the hot bucket reaches the trip value. The alarm threshold can be set to a trip value of 60% to 99%. After receiving the alarm, the operator can avoid tripping by reducing the load or activating the load shedding function.