Motor & Starter Protection
21
Over Voltage
Becomes operational only after start signal. Trips the
starter when main voltage increases above the set Over
Voltage Trip (OVT) Level for an adjustable period of
time longer than Over Voltage Delay (OVD).
Range: 150 – 750V (phase to phase)
Over Voltage Delay, Range: 1-10 sec.
Phase loss (and Under / Over Frequency)
Becomes operational when starter is energized and
protects motor from single phasing. Trips the starter
when 1 or 2 phases are missing for more than 1 sec.
Starter will also trip when frequency is less than 40 or
greater than 65Hz.
Note: Phase loss might not be detected in
lightly loaded motors.
Phase Sequence
Becomes operational when starter is energized,
provided this protection has been activated (Fault
Enable – Phase Sequence Protection, see Fault
Parameters). Trips the starter when phase sequence is
wrong.
Long Slow-Speed Time
Trips the starter if motor operates at slow speed for a
time longer than “Maximum Slow Speed Time”
Range: 1-30 sec. (consult factory for extended range).
Note: Operate motor at slow speed for the
minimum possible time to prevent
overheating. When motor operates at
slow speed, it draws higher than nominal
current (depending on Slow-Speed
Torque adjustment) thus, motor and
starter may overheat.
Wrong Connections
Become operational after start signal. Trips if motor is
not properly connected to starter’s Load terminals, or
when:
Internal disconnection in the motor winding is
detected.
Shorted SCR
Trips the starter in case one or more SCRs have been
shorted.
Heatsink Over Temperature
Thermal sensors are mounted on the heatsink and trip
the starter when temperature rises above 85ºC.
WARNING
The over temperature protection is designed to
operate under normal conditions e.g. in the event of
extended low overload, insufficient ventilation – fan
stoppage or air flow blockage.
Incorrect starter selection or operation frequents
starting at max. conditions, or repeated starting under
fault conditions can cause SCRs to overheat and fail
before
the heatsink reaches 85°C to trip the thermal
sensors.
External Fault
Becomes operational when starter is energized, trips
the starter when an External Contact closes for more
than 2 sec.
WARNING
Do not use External Fault when terminal 21 is not
connected to ground.
Fault and Reset
When any of the above protection (except Insulation
Alarm) operates, the starter locks in a fault condition,
disabling thyristors firing. Fault LED lights up, fault
description is displayed on the LCD and Fault Relay
operates.
• For local resetting, after fault has been
removed, press Reset key.
• Remote resetting can be done through
terminals 7 or 8 (see I/O Programming).
When Fault occurs, followed by a voltage outage, fault
condition is latched and reappears upon voltage
restoration.
Note:
Resetting is not possible
as long as Start signal exists.
Auto Reset
Under-voltage and Phase-loss, faults can be set to
Auto-Reset (see Fault Parameters). The starter will
reset itself 60 sec. after voltage was fully restored
provided no start signal exists.
Note:
Auto- Resetting is not possible
as long as Start signal
exists.
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