Safety instructions
Thermal motor monitoring
Description
2
2.2
2.2.1

2.2−1
EDSVF9383V EN 7.1−04/2012
2.2 Thermal motor monitoring
2.2.1 Description
 Note!
From software version 8.1 onwards, the 9300 vector controllers
are provided with an I
2
xt function for sensorless thermal
monitoring of the connected motor.
Æ’ I
2
xt monitoring is based on a mathematical model which
calculates a thermal motor utilisation from the detected
motor currents.
Æ’ The calculated motor utilisation is saved when the mains is
switched off.
Æ’ Nevertheless, I
2
xt monitoring does not provide full motor
protection because other influences on the motor utilisation
such as changes in the cooling conditions (e.g. cooling air flow
interrupted or too warm) cannot be detected.
The I
2
× t−load of the motor is constantly calculated by the drive controller
and displayed in C0066.
The I
2
x t−monitoring is designed in a way, that a motor with a thermal motor
time factor of 5 min, a motor current of 1.5 x I
r
and a trigger threshold of
100 % releases the monitoring after 179 s.
You can set different reactions with two adjustable trigger thresholds.
Æ’ Adjustable reaction OC8 (TRIP, Warning, Off).
– The reaction is set in C0606.
– The trigger threshold is set in C0127.
– The reaction OC8 can be used for example for an advance warning.
ƒ Fixed reaction OC6−TRIP.
– The trigger threshold is set in C0120.
Response of the I
2
x t−monitoring Condition
The I
2
x t−monitoring is deactivated.
C0066 = 0 % and
MCTRL−LOAD−I2XT = 0,00 % is set.
Set the controller inhibit at C0120 = 0 % and
C0127 = 0 %.
The I
2
x t−monitoring is stopped.
The actual value in C0066 and at the
MCTRL−LOAD−I2XT output is held.
Allow controller release at C0120 = 0 % and
C0127 = 0 %.
The I
2
x t−monitoring is deactivated.
The motor load is displayed in C0066.
Set C0606 = 3 (Off) and C0127 > 0 %.
 Note!
An OC6 or OC8 error message can only be reset if the
I
2
× t−monitoring has fallen below the set trigger threshold by
5 %.
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