Danfoss VLT AutomationDrive FC 300 Series Programming Manual page 48

Parameter Descriptions
1-90 Motor Thermal Protection
Option: Function:
[8] ETR trip 3
[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
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 3.12 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 [2] Thermistor Trip
Set 1-93 Thermistor Source to [6] Digital Input
®
VLT AutomationDrive Programmming Guide
®
AutomationDrive
 [°C]
 nominel +5°C
 nominel
®
MG33ME02 - VLT is a registered Danfoss trademark
39 42 50 53 54 55
12 13 18 19 27 29 32 33 20 37
PTC / Thermistor
Illustration 3.13
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
39 42 50 53 54 55
PTC / Thermistor
Illustration 3.14
Input Supply Voltage
Digital/analog
Digital 10 V
Analog 10 V
Table 3.7
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).
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
α cu = 0.00393
47
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