Illustration 2.30
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 1-90 Motor Thermal Protection to [2] Thermistor Trip
Set 1-93 Thermistor Source to [2] Analog Input 54
Do not select a reference source.
Illustration 2.31
Input
Digital/analog
Supply Voltage V
Cut-out Values
Threshold
Cut-out Values
Digital 24
< 6.6k
Ω
- > 10.8k
Ω
Digital 10
< 800
Ω
- > 2.7k
Ω
Analog 10
< 3.0k
Ω
- > 3.0k
Ω
Table 2.16
NOTE
Check that the chosen supply voltage follows the specifi-
cation 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.
ETR is activated in 1-90 Motor Thermal Protection and is
controlled in 4-16 Torque Limit Motor Mode. The time
before the torque limit warning trips the frequency
converter is set in 14-25 Trip Delay at Torque Limit.
Introduction
VLT
®
Refrigeration Drive Design Guide
MG16G102 - VLT
®
is a registered Danfoss trademark 35
2
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