Speed Bypass - Danfoss VLT HVAC Basic Drive Programming Manual

Parameters
NOTE
This parameter cannot be adjusted while the motor is
running.

3.5.3 4-6* Speed Bypass

3 3
Define the Speed Bypass areas for the ramps. Some systems
call for avoiding certain output frequencies or speeds, due to
resonance problems in the system. Three frequency ranges
can be avoided.
4-61 Bypass Speed From [Hz]
Array [3]
Range:
0.0 Hz [0.0 - 400.0 Hz] Some systems call for avoiding certain
*
4-63 Bypass Speed To [Hz]
Array [3]
Range:
0.0 Hz [0.0 - 400.0 Hz] Some systems call for avoiding certain
*
3.5.4 Semi-Automatic Bypass Speed Set-up
The Semi-Automatic Bypass Speed Set-up can be used to
facilitate the programming of the frequencies to be skipped
due to resonances in the system.
The following process is to be carried out:
1. Stop the motor.
NOTE
Please note that smaller frequency converters have a ramp
time of 3 seconds which can make it difficult to set the
bypass speeds. Please adjust the ramp times in 3-41 Ramp 1
Ramp up Time and 3-42 Ramp 1 Ramp Down Time.
2. Select Enabled in 4-64 Semi-Auto Bypass Set-up.
3. Press [Hand On] on the LCP to start the search for
frequency bands causing resonances. The motor
will ramp up according to the ramp set.
NOTE
Please note that terminal 27 Digital Input 5-12 Terminal 27
Digital Input has coast inverse as default setting. This means
that [Hand On] will not start the motor if there is no 24V to
terminal 27, so please connect terminal 12 to terminal 27.
34
VLT HVAC Basic Drive Programming Guide
Function:
output speeds due to resonance
problems in the system. Enter the lower
limits of the speeds to be avoided.
Function:
output speeds due to resonance
problems in the system. Enter the upper
limits of the speeds to be avoided.
MG.18.B1.02 - VLT
4. When sweeping through a resonance band, press
[OK] on the LCP when leaving the band. The actual
frequency will be stored as the first element in
4-63 Bypass Speed To [Hz] (array). Repeat this for
each resonance band identified at the ramp-up
(maximum three can be adjusted).
5. When maximum speed has been reached, the
motor will automatically begin to ramp-down.
Repeat the above procedure when speed is leaving
the resonance bands during the deceleration. The
actual frequencies registered when pressing [OK]
will be stored in 4-61 Bypass Speed From [Hz].
6. When the motor has ramped down to stop, press
[OK]. The 4-64 Semi-Auto Bypass Set-up will
automatically reset to Off. The frequency converter
will stay in Hand On mode until [Off] or [Auto On] is
pressed on the LCP.
If the frequencies for a certain resonance band are not
registered in the right order (frequency values stored in By
Pass Speed To are higher than those in By Pass Speed From) or
if they do not have the same numbers of registrations for the
By Pass From and By Pass To, all registrations will be cancelled
and the following message is displayed: Collected speed areas
overlapping or not completely determined. Press [Cancel] to
abort.
4-64 Semi-Auto Bypass Set-up
Option:
[0] Off
*
[1] Enable
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Function: