Danfoss VLT FC 102 Programming Manual page 69

Parameter Descriptions
1-90 Motor Thermal Protection
Option: Function:
[20] ATEX ETR
[21] Advanced ETR
ETR functions 1-4 calculate the load when the set-up
where they were selected is active. For example, ETR-3
starts calculating when set-up 3 is selected. For the North
American market: The ETR functions provide class 20
motor overload protection in accordance with NEC.
t [s]
2000
1000
600
500
400
300
200
100
60
50
40
30
20
10
1.0 1.2 1.4 1.6 1.8
Illustration 3.10 Thermal Motor Protection
NOTICE
If the temperature of the motor is monitored through a
thermistor or a KTY Sensor, the PELV is not complied
with in case of short circuits between motor windings
and the sensor. To comply with PELV, isolate the sensor
appropriately.
NOTICE
Danfoss recommends using 24 V DC as thermistor supply
voltage.
NOTICE
The ETR timer function does not work when
parameter 1-10 Motor Construction=[1] PM, non-salient
SPM.
NOTICE
For correct operation of the ETR function, the setting in
parameter 1-03 Torque Characteristics must fit the
application (see description of parameter 1-03 Torque
Characteristics).
M0010001
Programming Guide
f OUT = 1 x f M,N (par. 1-23)
f OUT = 2 x f M,N
f OUT = 0. 2 x f M,N
I
M
I (par. 1-24)
2.0
MN
Danfoss A/S © 10/2019 All rights reserved.
3.3.13.1 PTC Thermistor Connection
R
(Ω)
4000
3000
1330
550
250
-20 °C  nominal -5 °C
Illustration 3.11 PTC Profile
Example using a digital input and 10 V as supply
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 [6] Digital
Input.
39 42 50 53 54 55
12 13 18 19 27 29 32 33 20 37
PTC / Thermistor
Illustration 3.12 PTC Thermistor Connection - Digital Input
Example using an analog input and 10 V as supply
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.
 [°C]
 nominal +5 °C
 nominal
OFF
ON
R
<800 Ω >2.7 kΩ
67
3 3