Honeywell SmartVFD HVAC2 Applications Manual page 161

Motor thermal protection
0 =
No action
1 =
Alarm
2 =
Fault, stop function
3 =
Fault, coast "Stop function" on
page 132
If tripping is selected the drive will stop
and activate the fault stage, if the tem-
perature 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 frequencies 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 small.
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
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 display.
CAUTION! The calculated model does not
protect the motor if the airflow to the
motor is reduced by blocked air intake
grill.
NOTE: To comply with UL 508C requirements
motor over-temperature sensing is
required at installation if the parameter
is set to 0.
NOTE: If you use long motor cables (max. 100m)
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. Con-sider this when setting
up the motor thermal protection func-
tions.
161
specifies
T
31-00108—07