Danfoss VLT Refrigeration Drive FC 103 Programming Manual page 52

Parameter Description
1-90 Motor Thermal Protection
Option:
3 3
[0] No
protection
[1] Thermistor
warning
[2] Thermistor
trip
[3] ETR warning
1
[4] ETR trip 1
[5] ETR warning
2
[6] ETR trip 2
[7] ETR warning
3
[8] ETR trip 3
[9] ETR warning
4
[10] ETR trip 4
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.
50
®
VLT
Function:
See chapter 3.3.12.1 PTC Thermistor
Connection.
•
Via calculation (ETR=electronic
thermal relay) of the thermal load,
based on the actual load and time.
The calculated thermal load is
compared with the rated motor
current I and the rated motor
M,N
frequency f . The calculations
M,N
estimate the need for a lower load
at lower speed due to less cooling
from the fan incorporated in the
motor. See chapter 3.3.12.2 ETR.
•
Via a mechanical thermal switch
(Klixon type). See
chapter 3.3.12.3 Klixon. The ETR
provides class 20 motor overload
protection in accordance with NEC.
If the motor is continuously overloaded, and
no warning or trip of frequency converter is
wanted.
Activates a warning when the connected
thermistor in the motor reacts in the event of
motor overtemperature.
Stops (trips) the frequency converter when
the connected thermistor in the motor reacts
in the event of motor overtemperature.
Danfoss A/S © 05/2016 All rights reserved.
Refrigeration Drive FC 103
t [s]
2000
1000
600
500
400
300
200
100
60
50
40
30
20
10
1.0
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).
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
1.6 1.8 2.0
1.2 1.4
I
M
(par. 1-24)
MN
MG16H202