5-102 M60 Motor Protection System GE Multilin
5.4 SYSTEM SETUP 5 SETTINGS
5
• 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.
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