Danfoss VLT CDS302 Operating Instructions Manual page 120

Parameter Descriptions
28-24 Warning Level
Range:
130 [10–
*
28-26 Emergency
Level]
28-25 Warning Action
Option:
6 6
[0] None
[1] Decrease
*
cooling
28-26 Emergency Level
Range:
145 [28-24 Warning
*
Level-300]
28-27 Discharge Temperature
Range:
0 [-2147483648 –
*
2147483648]
6.15.4 28-3* Crankcase Heating
A DC-hold Current through the motor windings can be
used as an alternative to an external crankcase heater to
keep the compressor warm when stopped.
The efficiency of the Crankcase Heating depends upon the
physical placing of the actual motor in the compressor.
If the Crankcase Heating is used together with Anti-Reverse
Protection then the drive will first brake for the set
duration followed by the heating current.
28-30 Crankcase Heating Control
Option:
[0] Disabled
*
120
Operating Instructions VLT
Function:
Selects the temperature at which a
warning shall be issued. The action
selected in 28-25 Warning Action
becomes active at this temperature.
Enter the temperature measured in
the unit selected in
28-21 Temperature Unit.
Function:
Selects the action to be taken by the
frequency converter for discharge temper-
atures above the value programmed in
28-21 Temperature Unit but below the value
programmed in 28-26 Emergency Level.
No action. Only a warning will be issued.
A warning is issued and the motor speed is
lowered in steps of 10 Hz every 3 minutes
until the temperature either drops below the
level programmed in 28-24 Warning Level or
exceeds the level programmed in
28-26 Emergency Level.
Function:
Selects the temperature at which an
alarm shall be issued. Enter the
temperature in the unit programmed
in 28-21 Temperature Unit.
Function:
Returns the actual value of the
discharge temperature.
Function:
Activate the DC-hold current when the motor is
stopped. The current level is defined in
28-31 Heating DC Current.
MG34M302 - VLT
®
CDS302 and CDS303
28-30 Crankcase Heating Control
Option:
[1] Enabled
28-31 Heating DC Current
Range:
20% [0 – 25%] Set the DC-hold current as percentage of the
*
28-32 Crankcase Heating Delayed
Range:
5 s [5-65534 s] This time defines the delay after a stop and
*
6.15.5 28-4* Anti-reverse Protection
A compressor may have a preferred rotation direction and
the instructions for cabling should always be followed, but
the consequences of a reverse rotation are normally not
fatal. The parameter group 28-4* Anti-reverse Protection can
be set up to prevent reverse rotation at stop by injecting a
DC-brake current into the motor a few seconds after stop
followed by the eventual coast of the motor when the
discharge valve has closed.
NOTE
The DC-brake Function is not operational before any Start
Function has completed. In case of an emergency stop
before the starting sequence has completed then the
compressor may rotate reverse for a short moment after
stop. Under normal circumstances the correct sequence is
ensured by the Short Cycle Protection feature.
28-40 Reverse Protection Control
Option:
[0] Disabled
*
[1] Enabled
28-41 DC Brake Current
Range:
90% [0 – max motor
*
current ]
28-42 DC Braking Time
Range:
2.0 Sec
*
®
is a registered Danfoss trademark/Commercial Compressor
Function:
Function:
rated motor current in 1-24 Motor Current.
Function:
until Crank Case Heating is applied to the
compressor.
Function:
Activate a DC-brake current when the motor is
stopped. The current level is defined in 28-41 DC
Brake Current. Not recommended for Piston
compressors.
Function:
Set the DC-brake current as
percentage of the rated motor
current in 1-24 Motor Current.
Function:
[0 – 60.0 Sec] Set the duration of the DC-brake
current.