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MOTOR
NOTE:
5–2
Setpoints > Control > Switching Device Control
is no longer possible, the Stopped and Tripped are then based on the monitoring of
current level.
The Motor Tripped condition is detected when Any Trip operand is asserted and the
current is below 2% of CT and the switching device is open. However, when the switching
device is not configured then the Motor Tripped condition is detected when Any Trip
operand is asserted and the current is below 2% of CT. Resetting of the Motor Tripped
can be done by resetting the trip condition.
The state machine initially sets the Motor Stopped operand, as the switching device is
open and motor current is less than 2% of CT. Also, to detect a Motor Stopped condition
it is important to first reset any trip or the Any Trip operand is deserted. When the
switching device is not configured the Motor Stopped condition is detected based on
current only. Also, for the case when motor condition or status is solely based on the
monitoring of currents, idling condition (current becomes ideally zero) during Motor
Running in synchronous motor application can result in the Motor Stopped instead of
Motor Running. To prevent this, the 869 must always be programmed to monitor the
status of the switching device by means of contact input of the relay.
Motor Starting is asserted if the previous motor status is Motor Stopped and a load
current greater than 2% of FLA is detected, the Motor Starting operand becomes true.
The Motor cannot start if the previous condition is Motor Tripped unless Any Trip is reset.
For normal motor starting, the Motor Starting condition remains asserted until currents
fall below FLA x Overload Factor setting. As soon as motor current falls below FLA x the
Overload Factor setting, the Motor Running operand is set. Also, the motor can only be in
the running condition when Motor Starting and Motor Overload are deserted and the
previous condition is either Motor Starting or Motor Overload.
If current rises above FLA x Overload Factor at that point, the Motor Overload operand is
set. If current then falls below FLA x Overload Factor, the Motor Overload operand is
reset and the Running operand is set in 2 Speed Motor applications, when the motor is
switched from speed 1 to speed 2, FLA and CT Primary will switch to "Speed2 Motor FLA"
and Speed2 CT Primary (both set under System > Motor > Setup). In addition, during the
transition from speed 1 to speed 2 it may be possible that the current drops below 2%
and the Motor Stopped status becomes true. To prevent this, if the previous status is
Running (or Starting or Overload) and the 2-Speed Motor Protection is "Enabled" and the
Speed2 Motor Switch is true, then the motor status (Motor Running, Starting or Overload)
will be maintained for 1 second. After 1 sec, if motor current is detected less than FLA x
OL setting, the Motor Running operand will remain maintained, otherwise either the
Overload or Stopped condition will be declared.
During transition from speed 2 to speed 1, if the previous status is Running (Starting or
Overload) and 2-Speed Motor Protection is "Enabled" and Speed2 Motor Switch is true,
then the motor status (Motor Running, Starting or Overload) will be maintained for
Speed2 Switch 2-1 Delay + 1 second.
In synchronous motors, an idling condition results in the current ideally equal to zero
during motor running condition, this can result in the Motor Stopped condition instead of
Motor Running. To prevent this, it is strongly recommended that the 869 is always
programmed to monitor the status of the switching device by means of contact input of
the relay.
MOTOR THERMAL CAPACITY USED
Range: 0 to 100%
Default: 0%
The Thermal Capacity Used value is continuously calculated and displayed when the
thermal model element is enabled. When RTD Bias is enabled, this value shows the
biased thermal capacity used.
) the monitoring of switching device status
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: STATUS
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