Danfoss VLT FC 102 Series Design Manual page 59

Introduction to VLT® HVAC D...
39 42 50 53 54 55
12 13 18 19 27 29 32 33 20 37
PTC / Thermistor
Figure 2.43 Using a Digital Input and 10 V as Power Supply
Using an analog input and 10 V as power supply:
Example: The adjustable frequency drive 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.
Figure 2.44 Using an Analog Input and 10 V as Power Supply
Input Supply Voltage V
Digital/analog Cut-out Values
Digital 24
Digital 10
Analog 10
Table 2.26 Threshold Cut-out Values
NOTICE!
Ensure that the chosen supply voltage follows the
specification of the thermistor element utilized.
MG11BC22
Design Guide
OFF
ON
R
<800 Ω >2.7 kΩ
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.
Summary
With the torque limit feature the motor is protected for
being overloaded independent of the speed. With the ETR,
the motor is protected from being overheated 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 to prevent overheating. If
the motor is overloaded without reaching the temperature
where the ETR shuts off the motor, the torque limit
protects the motor and application for becoming
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 adjustable
frequency drive is set in 14-25 Trip Delay at Torque Limit.
2 2
57