Section 4. Configuration of the frequency converter
4.5. Motor drying function
Applies to devices with software version 12.63 and above.
The software version can be checked in parameter 0.51.
The motor drying function is used to heat the motor windings when stopped. Keeps the engine warm,
dehumidifies from possible moisture and prevents condensation.
The motor is heated by forcing a direct current to flow through the motor windings. The value of this current is
set in
par. 1.97
and can be in the range from 0% to 60% of the current rated motor (the rated motor current is given in
par. 1.3).
The drying function can only be activated when the motor is stopped. Starting the converter frequency stops
the drying function and resets the time remaining until the end of drying (
par. 0.38
). When restarting the drying function,
the countdown of time will start from the value stored in
par. 1.99
.
The ongoing process of drying the motor is signaled by the flashing green led RUN.
Note 1: Using the motor drying function without monitoring the temperature of the motor windings may result to
windings overheating and motor damage.
Note 2: Setting the maximum drying time in
par. 1.99
at 200.0 h means, disabling the automatic end of drying function -
the timer will count down from 200.0 h to 0 h, but after it has expired will not finish the drying process. The drying
process will only be finished when one of the following conditions occurs:
• "start converter" command,
• no signal that allows the drying process -
par. 1.96
,
• operation blocking or converter failure.
Parameters responsible for the motor drying function:
Parameter /
Name
Function
Available options / measurement unit
Factory
setting
Change
during
operation
0.38
Dry end time
Time to the end of
the drying process
[min.]
---
---
---
1.96
DC dry enable
Switching On the
drying process
000 Sw.Off
– Switch off
001 In.C1 … In.C6
– switch on when on DI1..6
is given a voltage
007 Sw.On
– Switch on
The drying process is switched on with the
rising edge – fig. 4.21
000 Sw.Off
Yes
1.97
DC dry max I
Drying current limit
0..60.0%
Note: this is the limit of the average value of the
current from the three phases. In one of the
motor phases, the current value will be higher
and may be up to 1.5 times the current value
set in parameter 1.97.
20.0 %
Yes
1.98
DC dry max U
Drying voltage limit
0..40.0%
5.0 %
Yes
1.99
DC dry time
Maximum drying
time
0.1..200.0 h
Note: the value of 200.0 h means that the
automatic end of drying function is turned off -
the timer will count down the time from 200.0 h
to 0 h, but after it finish, it will not end the drying
process.
0.1 h
Yes
The state of the motor drying process can be read in register 2007, bit 1 - see chapter 13.2
Map of registers available
through the RS interface
.
The address
of the
registers
(decimal)
Description (meaning)
Mode
2007
bit 1 = 1 - the motor drying process is in progress
Read only
42
Frequency converter MFC710 type. TWERD Power Electronics
