64 Functional Description Emotron AB 01-4429-01r2
11.2.5 Motor Protection [230]
This function protects the motor against overload based on
the standard IEC 60947-4-2.
Motor I
2
t Type [231]
The motor protection function makes it possible to protect
the motor from overload as published in the standard IEC
60947-4-2. It does this using Motor I2t Current, [232] as a
reference. The Motor I2t Time [233] is used to define the
time behaviour of the function. The current set in [232] can
be delivered infinite in time. If for instance in [233] a time
of 1000 s is chosen the upper curve of Fig. 60 is valid. The
value on the x-axis is the multiple of the current chosen in
[232]. The time [233] is the time that an overloaded motor
is switched off or is reduced in power at 1.2 times the cur-
rent set in [232].
Communication information
Motor I
2
t Current [232]
Sets the current limit for the motor I
2
t protection.
Communication information
Motor I
2
t Time [233]
Sets the time of the I
2
t function. After this time the limit for
the I
2
t is reached if operating with 120% of the I
2
t current
value. Valid when start from 0 rpm.
Communication information
Default: Trip
Off 0 I
2
t motor protection is not active.
Trip 1
When the I
2
t time is exceeded, the VSD will
trip on “Motor I
2
t”.
Limit 2
This mode helps to keep the inverter run-
ning when the Motor I2t function is just
before tripping the VSD. The trip is
replaced by current limiting with a maxi-
mum current level set by the value out of
the menu [232]. In this way, if the reduced
current can drive the load, the VSD contin-
ues running.
Modbus Instance no/DeviceNet no: 43061
Profibus slot/index 168/220
Fieldbus format UInt
Modbus format UInt
NOTE: When Mot I2t Type=Limit, the VSD can control the
speed < MinSpeed to reduce the motor current.
231 Mot I
2
t Type
Stp M1: Trip
Default: 100% of I
MOT
Range: 0–150% of I
MOT
Modbus Instance no/DeviceNet no: 43062
Profibus slot/index 168/221
Fieldbus format Long, 1=1%
Modbus format EInt
NOTE: When the selection Limit is set in menu [231], the
value must be above the no-load current of the motor.
NOTE: Not the time constant of the motor.
Default: 60 s
Range: 60–1200 s
Modbus Instance no/DeviceNet no: 43063
Profibus slot/index 168/222
Fieldbus format Long, 1=1 s
Modbus format EInt
233 Mot I
2
t Time
Stp M1: 60s