Danfoss FC 102 Design Manual page 53

Introduction to VLT® HVAC D...
Set 1-93 Thermistor Source to [6] Digital Input 33
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12 13 18 19 27 29 32 33 20 37
PTC / Thermistor
Illustration 2.43 Using a Digital Input and 10 V as Power
Supply
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.
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PTC / Thermistor
Illustration 2.44 Using an Analog Input and 10 V as Power
Supply
Input Supply Voltage
Digital/analog V
Cut-out Values
Digital 24
Digital 10
Analog 10
Table 2.26 Threshold Cut-out Values
NOTICE
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
MG11BC02
Design Guide
OFF
ON
R
<800 Ω >2.7 kΩ
OFF
ON
<3.0 k Ω R
>3.0 k Ω
Threshold
Cut-out Values
< 6.6 kΩ - > 10.8 kΩ
< 800 Ω - > 2.7 kΩ
< 3.0 kΩ - > 3.0 kΩ
Danfoss A/S © Rev. 06/2014 All rights reserved.
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 to prevent overheating. 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.
2 2
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