Motor Overtemperature Protection - WEG CFW-11 Programming Manual

Faults and Alarms
Note!
In order to assure the conformity of the CFW-11 motor overload protection with the UL508C standard,
observe the following:
"Trip" current equal to 1.25 times the motor nominal current (P0401) adjusted in the "Guided
Start-up" menu.
The maximum allowed value for the parameter P0159 (Motor Trip Class) is 3 (Trip Class 20).
The maximum allowed value for P0398 (Motor Service Factor) is 1.15.

15.2 MotoR oVeRteMPeRatURe PRotectioN

atteNtioN!
The PTC must have a reinforced insulation against the live parts of the motor and of the
installation.
This protection performs the motor overtemperature protection by means of the alarm (A110) and the fault
(F078) indication.
The motor must have a PTC type temperature sensor.
An analog output supplies constant current for the PTC (2 mA), while an inverter analog input reads the voltage
across the PTC and compares it with the limit values for fault and alarm. Refer to the table 15.1. When those
values are exceeded, the alarm or fault indication occurs.
The analog outputs AO1 and AO2 of the control module, as well as the analog outputs existent on the accessory
modules AO1-B and AO2-B (IOB) can be used to supply the constant current for the PTC. Therefore it is necessary
to configure the DIP switches of the output for current and to set the output function parameter for 13=PTC.
The analog inputs AI1 and AI2 of the control module, as well as the analog inputs existent on the accessory
modules AI3 (IOB) and AI4 (IOA) can be used to read the PTC voltage. Therefore it is necessary to configure
the input DIP switch for voltage and to set the input function parameter for 4=PTC. Refer to the parameter
P0351 on the section 15.3.
Note!
In order that this function works properly, it is important to keep gains and offset of the analog input
and output in the default values.
15
15-2
Table 15.1 - A110 and F078 trip levels
Action
A110 occurs during the temperature increase
F078 trips during the temperature increase
Resets A110 alarm
Allows the reset of the F078 fault
F078 trips (minimum resistance detection)
PTC AI voltage
R >3.51 kΩ
PTC
R >3.9 kΩ
PTC
150 Ω < R
<1.6 kΩ 0.3<V
PTC
150 Ω < R
<1.6 kΩ 0.3<V
PTC
<100 Ω
R
PTC
V >7.0 V
AI
V >7.8 V
AI
<3.2 V
AI
<3.2 V
AI
<0.2 V