Danfoss VLT HVAC Basic Drive FC 100 Series Programming Manual page 47

Parameters
3.5.5 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!
Smaller adjustable frequency drives have a ramp time of
three seconds which can make it difficult to set the bypass
speeds. Adjust the ramp times in 3-41 Ramp 1 Ramp Up
Time and 3-42 Ramp 1 Ramp Down Time.
2. Select [1] Enabled in 4-64 Semi-Auto Bypass Set-up.
3. Press [Hand On] to start the search for frequency
bands causing resonances. The motor will ramp
up according to the ramp set.
NOTE!
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 24 V to terminal 27,
so connect terminal 12 to terminal 27.
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 adjustable
frequency drive will stay in Hand On mode until
[Off] or [Auto On] is pressed.
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
canceled and the following message is displayed: Collected
speed areas overlapping or not completely determined. Press
[Cancel] to abort.
®
VLT HVAC Basic Drive Programming Guide
4-64 Semi-Auto Bypass Set-up
Option:
[0]
[1]
®
MG18B222 - VLT is a registered Danfoss trademark
Function:
Off
Enable
3 3
3-19