GE M60 UR Series Instruction Manual Download

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5-102

M60 Motor Protection System

GE Multilin

5.4 SYSTEM SETUP

5 SETTINGS

•

MOTOR OFFLINE:

This input

must be

connected to the appropriate external contact. This setting is selected to a con-

tact input that is connected to an auxiliary contact of the breaker or contactor used to switch the motor. The motor is
declared to be stopped when the phase current falls below 2% of motor full load current (FLA)

and

the external contact

indicates the switching device is open.

For example, a circuit breaker 52b auxiliary contact is closed when the breaker is open and open when the breaker is
closed. Therefore the setting should be "Cont Ip n On". For a 52a contact the setting should be "Cont Ip n Off".

Four mutually exclusive FlexLogic operands that reflect the motor state are generated by a state machine in the relay
to determine motor status. They are:

MOTOR OFFLINE

MOTOR STARTING

MOTOR RUNNING

, and

MOTOR OVERLOAD

The state machine initially sets the

MOTOR OFFLINE

operand, as the auxiliary contact reports the switching device is

open and motor current is less than 2% of FLA. If the previous motor status is offline and a phase current greater than
2% of FLA is detected and the MOTOR OFFLINE operand de-asserts, the

MOTOR STARTING

operand becomes true.

After 1 second, if motor current is less than FLA times the

MOTOR OVERLOAD FACTOR

setting, the

MOTOR RUNNING

operand is set (this accounts for the use of a soft-starter mechanism that slowly increases current such that it never
exceeds FLA



overload factor during a starting sequence). For normal starting, the

MOTOR STARTING

operand

remains set until the current falls below FLA



overload factor, at which time the

MOTOR RUNNING

operand is set. If

current rises above FLA



Service Factor at that point, the

MOTOR OVERLOAD

operand is set. If current then falls below

FLA



overload factor, the

MOTOR OVERLOAD

operand is reset and the

MOTOR RUNNING

operand is set. A

MOTOR

OFFLINE

state is determined per the logic noted above.

When two-speed motor functionality is employed, this setting is used to indicate the breaker or contactor position at
speed 1. As such, the speed 1 auxiliary contact is connected to the

input specified by this setting for two-speed appli-

cations.

•

EMERGENCY RESTART:

As the name implies, this feature should only be used in an emergency, as it defeats the

purpose of the relay – protecting the motor!. The input selected by this setting is used to reset the motor thermal
capacity used from its current value to 0% so that a hot motor may be restarted. However, trip conditions that are still
present (for example, hot RTD) will still cause a trip. In the event of a real emergency, the

EMERGENCY RESTART

oper-

and should remain at logic 1 until the emergency is over. Any

EMERGENCY RESTART

operand transition will be logged

as an event.

•

MOTOR LINE SOURCE:

This setting selects the source connected to phase current transformers on the power sys-

tem side of the stator winding.

•

NUMBER OF STARTS TO LEARN

: This setting selects number of motor start and stop records to average data pre-

sented in the

ACTUAL VALUES



RECORDS



MOTOR LEARNED DATA

menu.

•

MOTOR LOAD AVERAGE CALC. PERIOD

: This setting specifies the period of time over which parameter averages

are calculated. The calculation is a sliding window.

•

2-SPEED MOTOR PROTECTION

: This setting is used to enable the two-speed motor function. This function provides

proper protection for a two-speed motor where there are two different full load values. The two-speed functionality is
required for motors having two windings wound into one stator. One winding, when energized, provides one of the
speeds. When the second winding is energized, the motor takes on the speed determined by the second winding. The
M60 algorithm integrates the heating at each speed into one thermal model using a common thermal capacity used
register value for both speeds. Using the M60 for such applications provides several options, allowing the removal of
traditional wiring and interlocking:

–

Use the M60 front panel pushbuttons and provide necessary operate and interlock logic via FlexLogic.

–

Use external pushbuttons and provide necessary operate and interlock logic using FlexLogic as shown below.

–

Use a traditional external control schematic with some connections to the M60 for control and protection.

•

SPEED2 MOTOR SWITCH

: If the two-speed motor feature is used, this setting specifies a FlexLogic operand to indi-

cate the current motor speed. This is typically an indication that the contactor at speed 2 is energized. When the
assigned FlexLogic operand (typically a contact input operand) is asserted, the algorithm switches to speed 2 (high
speed). If the assigned FlexLogic operand is de-asserted, the algorithm switches to speed 1 (low speed). This allows
the M60 to determine which settings should be active at any given time. To maintain correct motor status indication, the
M60 expects a transition from speed 1 to speed 2 within two seconds; otherwise, the motor status value may be reset.

•

SPEED2 SWITCH 2-1 DELAY

: This setting specifies the time delay to transfer from high to low speed. This allows the

motor to slow down before energizing at low speed.