Motor Overtemperature Protection (F0078) - WEG CFW501 V1.8X Programming Manual

14.3 MOTOR OVERTEMPERATURE PROTECTION (F0078)

This function protects the motor against overtemperature through indication of fault F0078.
The motor needs a temperature sensor of the triple PTC type. The reading of the sensor can be done in two
different ways: through the analog input or through the digital input.
For the reading of the PTC via analog input, it is necessary to configure it for current input and select option
"4 = PTC" in P0231, P0236 or P0241. Connect the PTC between source +10 Vdc and the analog input, as
well as the AIx configuration DIP-Switch in "mA".
The analog input reads the PTC resistance and compares it to the limits values for the fault. When those values
are exceeded, fault F0078 is indicated, as shown in
on page 14-5.
ATTENTION!
The PTC must feature reinforced insulation of the live parts of the motor and installation.
NOTE!
For this function to work properly, it is important to keep the gain(s) and offset(s) of the analog inputs
at the standard values.
NOTE!
The DI2 is the only one that cannot be used as PTC input, because it has input circuit dedicated to
frequency input (FI).
Figure 14.3: PTC connection to the CFW501 via analog input on page 14-5
inverter terminals.
Table 14.1: Actuation level of fault F0078 PTC via analog input
Table 14.1: Actuation level of fault F0078 PTC via analog input
PTC Resistance
R < 50 Ω V
PTC IN
50 Ω < R < 3.9 kΩ 9.1 V > V
PTC
R > 3.9 kΩ V
PTC IN
PTC
Figure 14.3: PTC connection to the CFW501 via analog input
AIx Overtemperature
> 9.1 V F0078
> 1.3 V Standard
IN
< 1.3 V F0078
shows the PTC connection to the
+10 V
AIx
(DIP SWITCH = mA)
Faults and Alarms
CFW501 | 14-5
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