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Honeywell HVAC232 Series Applications Manual page 123


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Motor thermal protection (Mtp)
0 =
No action
1 =
2 =
Fault, stop function
3 =
Fault, coast „Stop function" on page 120
If tripping is selected the drive will stop and activate the fault stage,
if the temperature of the motor becomes too high. Deactivating the
protection, i.e. setting parameter to 0, will reset the thermal model
of the motor to 0%.
The motor thermal protection is to protect the motor from overheating. The
drive is capable of supplying higher than nominal current to the motor. If the
load requires this high current there is a risk that the motor will be thermally
overloaded. This is the case especially at low frequencies. At low frequen-
cies the cooling effect of the motor is reduced as well as its capacity. If the
motor is equipped with an external fan the load reduction at low speeds is
The motor thermal protection is based on a calculated model and it uses
the output current of the drive to determine the load on the motor.
The motor thermal protection can be adjusted with parameters. The thermal
current I
specifies the load current above which the motor is overloaded.
This current limit is a function of the output frequency.
The thermal stage of the motor can be monitored on the control keypad
The calculated model does not protect the motor if the airflow
to the motor is reduced by blocked air intake grill.
Application manual HVAC232/402 | Document 27-652 | Issue ENG06 | 2019-08-07
To comply with IEC 61800-5-1:2007+A1:2016 requirements
motor over-temperature sensing is required at installation if the
parameter is set to 0.
If you use long motor cables (max. 100 m) together with small
drives (<=1.5 kW) the motor current measured by the drive can
be much higher than the actual motor current due to capacitive
currents in the motor cable. Consider this when setting up the
motor thermal protection functions. .
Motor thermal protection (Mtp): Ambient temperature
When the motor ambient temperature must be taken into consideration, it is
recommended to set a value for this parameter. The value can be set be-
tween –20 and 100 degrees Celsius.

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