Danfoss VLT FC 302 Operating Instructions Manual page 55

Programming
1-90 Motor Thermal Protection
Option: Function:
the motor is overloaded. Programme a
warning signal via one of the digital outputs.
The signal appears in the event of a warning
and if the frequency converter trips (thermal
warning).
[5] ETR warning
2
[6] ETR trip 2
[7] ETR warning
3
[8] ETR trip 3
[9] ETR warning
4
[10] ETR trip 4
NOTICE
If [20] ATEX ETR is selected, follow the instructions
described in the dedicated chapter of the VLT
AutomationDriveFC 301/FC 302 Design Guide and the
instructions given by the motor manufacturer.
NOTICE
If [20] ATEX ETR is selected, set 4-18 Current Limit to
150%.
PTC Thermistor Connection
R
(Ω)
4000
3000
1330
550
250
 nominel -5°C
-20°C
Illustration 6.2 PTC profile
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:
MG37A202
Operating Instructions
®
 [°C]
 nominel +5°C
 nominel
Danfoss A/S © Rev. 2014-07-29 All rights reserved.
Set parameter 1-90 Motor Thermal Protection to [2]
Thermistor Trip
Set parameter 1-93 Thermistor Source to [6] Digital Input
39 42 50 53 54 55
12 13 18 19 27 29 32 33 20 37
PTC / Thermistor
Illustration 6.3 Example with Digital Input and 10 V 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 parameter 1-90 Motor Thermal Protection to [2]
Thermistor Trip
Set parameter 1-93 Thermistor Source to [2] Analog Input 54
39 42 50 53 54 55
PTC / Thermistor
Illustration 6.4 Example with Analog Input and 10 V Power
Supply
Input Supply Voltage
Digital/analog [V]
Digital 10
Analog 10
Table 6.2 Threshold Cut-out Values for Illustration 6.3 and Illustration 6.4
NOTICE
Check that the selected supply voltage follows the
specification of the thermistor element.
ETR
The calculations estimate the need for a lower load at
lower speed due to less cooling from the fan incorporated
in the motor.
OFF
ON
R
<800 Ω >2.7 kΩ
OFF
ON
<3.0 k Ω
R
>3.0 k Ω
Threshold
Cut-out Values
< 800 Ω - > 2.7 kΩ
< 3.0 kΩ - > 3.0 kΩ
53
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