Ptc Thermistor Connection; Kty Sensor Connection - Danfoss VLT AutomationDrive FC 300 Programming Manual

Parameter Descriptions
1-90 Motor Thermal Protection
Option: Function:
[9] ETR warning
4
[10] ETR trip 4
[20] ATEX ETR Activates the thermal monitoring function for
Ex-e motors for ATEX. Enables 1-94 ATEX ETR
cur.lim. speed reduction, 1-98 ATEX ETR interpol.
points freq. and 1-99 ATEX ETR interpol points
current.
[21] Advanced
ETR
NOTE
If [20] is selected, follow strictly the instructions described in
the dedicated chapter of the VLT AutomationDrive design
guide and the instructions given by the motor manufacturer.
NOTE
If [20] is selected, 4-18 Current Limit must be set to 150%.

3.3.10.1 PTC Thermistor Connection

R
(Ω)
4000
3000
1330
550
250
 nominel -5°C
-20°C
Illustration 3.4 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:
Set 1-90 Motor Thermal Protection to Thermistor Trip [2]
Set 1-93 Thermistor Source to Digital Input [6]
FC 300 Programming Guide
 [°C]
 nominel +5°C
 nominel
®
MG.33.MB.02 - VLT is a registered Danfoss trademark
39 42 50 53 54 55
12 13 18 19 27 29 32 33 20 37
PTC / Thermistor
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 Thermistor Trip [2]
Set 1-93 Thermistor Source to Analog Input 54 [2]
39 42 50 53 54 55
PTC / Thermistor
Input Supply Voltage
Digital/analog
Digital 10V
Analog 10V
NOTE
Check that the chosen supply voltage follows the specifi-
cation of the used thermistor element.

3.3.10.2 KTY Sensor Connection

(FC 302 only)
KTY sensors are used especially in Permanent Magnet Servo
Motors (PM motors) for dynamic adjusting of motor
parameters as stator resistance (1-30 Stator Resistance (Rs))
for PM motors and also rotor resistance (1-31 Rotor Resistance
(Rr)) for asynchronous motors, depending on winding
temperature. The calculation is:
where
Rs = Rs 20° C x (1 + α cu x Δ T ) Ω
KTY sensors can be used for motor protecting (1-97 KTY
Threshold level).
FC 302 can handle three types of KTY sensors, defined in
1-95 KTY Sensor Type. The actual sensor temperature can be
read out from 16-19 KTY sensor temperature.
OFF
ON
R
<800 Ω >2.7 kΩ
OFF
ON
<3.0 k Ω
R
>3.0 k Ω
Threshold
Cut-out Values
< 800Ω - > 2.7kΩ
< 3.0 kΩ - > 3.0kΩ
α cu = 0.00393
45
3 3