Danfoss VLT HVACDrive User Manual

When par. 1-73 Flying Start is enabled, par. 1-71 Start Delay has no function.
Search direction for flying start is linked to the setting in par. 4-10
Motor Speed Direction .
Clockwise [0]: Flying start search in clockwise direction. If not successful, a DC brake is carried out.
Both Directions [2]: The flying start will first make a search in the direction determined by the last
reference (direction). If unable to find the speed, it will search in the other direction. If not suc-
cessful, a DC brake will be activated in the time set in par. 2-02
DC Braking Time . Start will then
take place from 0 Hz.
[0] * Disabled Select
Disable [0] if this function is not required
[1] Enabled Select
Enable [1] to enable the adjustable frequency drive to “catch” and control a spinning motor.
1-80 Function at Stop
Option: Function:
Select the adjustable frequency drive function after a stop command or after the speed is ramped
down to the settings in par. 1-81
Min Speed for Function at Stop [RPM] .
[0] * Coast Leaves motor in free mode.
[1] DC Hold/Motor Preheat Energizes motor with a DC holding current (see par. 2-00
DC Hold/Preheat Current ).
1-86 Trip Speed Low [RPM]
Range: Function:
0 RPM* [Application dependant] If the trip speed is set to 0, the function is not active.
If the speed after the start (or during a stop) falls below the value in the parameter at any time,
the drive will trip with an alarm [A49] Speed Limit. Function at stop.
NOTE!
This parameter is only available if par. 0-02
Motor Speed Unit is set to [RPM].
1-87 Trip Speed Low [Hz]
Range: Function:
0.0 Hz* [Application dependant] If the trip speed is set to 0, the function is not active.
If the speed after the start (or during a stop) falls below the value in the parameter at any time,
the drive will trip with an alarm [A49] Speed Limit. Function at stop.
NOTE!
This parameter is only available if par. 0-02
Motor Speed Unit is set to [Hz].
1-90 Motor Thermal Protection
Option: Function:
The adjustable frequency drive determines the motor temperature for motor protection in two dif-
ferent ways:
• Via a thermistor sensor connected to one of the analog or digital inputs (par. 1-93
Ther-
mistor Source
).
• 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
VLT
®
HVAC Drive Instruction Manual
7 How to Program the Adjustable Frequency
Drive
MG.11.AB.22 - VLT
®
is a registered Danfoss trademark 7-17
7

Danfoss VLT HVACDrive Specifications

General

Brand	Danfoss
Model	VLT HVACDrive
Category	DC Drives
Language	English