Digistart D3: User Guide
25
Issue: G
4.1.7 Motor Thermistors
Motor thermistors can be connected directly to the Digistart D3. The soft starter will trip when the resistance of the
thermistor circuit exceeds approximately 3.6 k
Ω
or falls below 20
Ω
.
If no motor thermistors are connected to the Digistart D3 thermistor input terminals TH1, TH2 must be open. If TH1,
TH2 are shorted, the Digistart D3 will trip.
The thermistor input is disabled by default, but activates automatically when a thermistor is detected. If thermistors
have previously been connected to the Digistart D3 but are no longer required, either:
•
connect a 1.2 k
Ω
resistor between TH1, TH2 or
•
reset the starter to factory defaults (see
Load defaults
). If you wish to retain the starter’s configuration, save
the starter’s settings to a user set before resetting. Reload the settings after the thermistor input has been
reset
NOTE
The thermistor circuit should be run in screened cable and must be electrically isolated from ground and all
other power and control circuits.
4.1.8 Programmable inputs
The default setting of programmable input A is 'Starter Disable' (Pr 3A).
If the Starter Disable function is not
required, change the setting of Pr 3A or connect a link across DI4, +24V.
If programmable input A is set to 'Starter Disable', the circuit must be closed for the starter to operate. An open circuit
across DI4, +24V will disable the starter. The Digistart D3 will not respond to start commands. If running, the soft
starter will allow the motor to coast to stop, ignoring the soft stop mode set in Pr 2H.
