Danfoss FC 300 Programming Manual page 51

FC 300 Programming Guide
2.4.9. 1-9* Motor Temperature
Parameters for setting the temperature protection features for the motor.
1-90 Motor Thermal Protection
Option:
*
No protection
[0]
[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
Motor protection can be implemented using a range of techniques: PTC or KTY sensor (see also section
mechanical thermal switch (Klixon type); or Electronic Thermal Relay (ETR).
Using a digital input and 24 V as power supply:
Example: The frequency converter trips when the motor temperature is too high
Parameter set-up:
Motor Thermal Protection
Set Par. 1-90
Thermistor Source
Set Par. 1-93
Function:
The frequency converter determines the motor temperature for motor protection in two different ways:
• Via a thermistor sensor connected to one of the analog or digital inputs (par. 1-93
Source
).
• Via calculation (ETR = Electronic Terminal Relay) of the thermal load, based on the actual load and
time. The calculated thermal load is compared with the rated motor current I
frequency f . The calculations estimate the need for a lower load at lower speed due to less cool-
M,N
ing from the fan incorporated in the motor.
Continuously overloaded motor, when no warning or trip of the frequency converter is required.
Activates a warning when the connected thermistor or KTY-sensor in the motor reacts in the event of motor
over-temperature.
Stops (trips) frequency converter when connected thermistor in motor reacts in the event of motor over-tem-
perature.
The thermistor cut-out value must be > 3 kΩ.
Integrate a thermistor (PTC sensor) in the motor for winding protection.
Thermistor Trip
to [2]
Digital Input
to [6]
®
MG.33.M3.02 - VLT is a registered Danfoss trademark
2. How to Programme
Thermistor
and the rated motor
M,N
KTY Sensor Connection ) in motor windings;
2
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