Danfoss VLT HVAC Operating Instructions Manual page 68

6. How to programme the frequency converter
Function:
This function makes it possible to catch a mo-
tor which is spinning freely due to a mains
drop-out.
Description of choice:
Select
quired.
Select
verter to "catch" and control a spinning motor.
When par. 1-73 is enabled, par. 1-71
Delay
Search direction for flying start is linked to the
setting in par. 4-10, Motor Speed Direction.
Clockwise
6
direction. If not successful, a DC brake is car-
ried out.
Both Directions
make a search in the direction determined by
the last reference (direction). If not finding
the speed it will make a search in the other
direction. If not successful, a DC brake will be
activated in the time set in par. 2-02, Braking
Time. Start will then take place from 0 Hz.
1-80
Value:
Coast
DC hold/Preheat
Function:
Select the frequency converter function after
a stop command or after the speed is ramped
down to the settings in par. 1-81
for Function at Stop [RPM]
Select
mode.
Select
motor with a DC holding current (see par.
2-00).
1-90
Value:
No protection
Thermistor warning
Thermistor trip
ETR warning 1
ETR trip 1
ETR warning 2
68
Disable
[0] if this function is not re-
Enable
[1] to enable the frequency con-
has no function.
[0]: Flying start search in clockwise
[2]: The flying start will first
Function at Stop
.
Coast
[0] to leave the motor in free
DC hold/Preheat
[1] to energize the
Motor Thermal Protection
MG.11.A4.02 - 09.10.06. VLT
ETR trip 2
ETR warning 3
ETR trip 3
ETR warning 4
ETR trip 4
Function:
The frequency converter determines the mo-
tor temperature for motor protection in two
different ways:
Start
• Via a thermistor sensor connected to
one of the analog or digital inputs
(par. 1-93
• Via calculation (ETR = Electronic
Thermal Relay) of the thermal load,
based on the actual load and time.
The calculated thermal load is com-
pared with the rated motor current
I
M,N
f
M,N
need for a lower load at lower speed
due to less cooling from the fan in-
corporated in the motor.
No protection
Select
tinuously overloaded and no warning or trip of
frequency converter is wanted.
Thermistor warning
Select
warning when the connected thermistor in the
motor reacts in the event of motor over-tem-
[0]
perature.
[1]
Thermistor trip
Select
frequency converter when the connected
thermistor in the motor reacts in the event of
motor over-temperature.
The thermistor cut-out value is > 3 kΩ.
Min Speed
Integrate a thermistor (PTC sensor) in the
motor for winding protection.
[0]
[1]
[2]
Motor protection can be implemented using a
[3]
range of techniques: PTC sensor in motor
[4]
[5]
® is a registered Danfoss trademark
®
VLT HVAC Drive Operating Instructions
Thermistor Source
).
and the rated motor frequency
. The calculations estimate the
[0] if the motor is con-
[1] to activate a
[2] to stop (trip) the
[6]
[7]
[8]
[9]
[10]