Danfoss VLT HVAC Drive FC 100 Series Design Manual page 47

®
VLT HVAC Drive Design Guide
Using a digital input and 10 V as power supply:
Example: The frequency converter trips when the motor temperature is
too high.
Parameter set-up:
Thermal Protection
Set par. 1-90 Motor
Source
Set par. 1-93 Thermistor to
Using an analog input and 10 V as power supply:
Example: The frequency converter trips when the motor temperature is
too high.
Parameter set-up:
Set par. 1-90 Motor Thermal Protection
Set par. 1-93 Thermistor Source to
Do not select a reference source.
Input
Digital/analog
Digital
Digital
Analog
NB!
Check that the chosen supply voltage follows the specification of the used thermistor element.
Summary
With the Torque limit feature the motor is protected for being overloaded independent of the speed. With the ETR the motor is protected for being over
heated and there is no need for any further motor protection. That means when the motor is heated up the ETR timer controls for how long time the
motor can be running at the high temperature before it is stopped in order to prevent over heating. If the motor is overloaded without reaching the
temperature where the ETR shuts of the motor, the torque limit is protecting the motor and application for being overloaded.
NB!
ETR is activated in par. 1-90 Torque Limit
in par. 14-25.
Thermistor Trip
to [2]
Digital Input 33
[6]
to Thermistor Trip [2]
Analog Input 54 [2]
Supply Voltage
Volt
24 V
10 V
10 V
and is controlled in par. 4-16. The time before the torque limit warning trips the frequency converter is set
MG.11.B7.02 - VLT ® is a registered Danfoss trademark
2. Introduction to VLT HVAC Drive
Using a digital input and 24 V as power supply:
Example: The frequency converter trips when the motor temperature is
too high.
Parameter set-up:
Thermal Protection
Set par. 1-90 Motor
Source Digital Input 33
Set par. 1-93 Thermistor to
Threshold
Cut-out Values
< 6.6 kΩ - > 10.8 kΩ
< 800Ω - > 2.7 kΩ
< 3.0 kΩ - > 3.0 kΩ
Thermistor Trip
to [2]
[6]
2
47