Engineering manual - UniSAB III 1.10.8
001930 en 2021.06
123/346
Compressor control and surveillance
Stopping sequence
At normal stop (to avoid back-spin) the SSTV valve is closed for the time stated in the timer SSTV delay
before the compressor is stopped. The default setting is 40 seconds but it is adjustable between 0 and
60 seconds.
Note: The SSTV timer starts counting after the stop delay timer has run out. This means that the com-
pressor will not stop immediately even though the stop key is pressed or the instant stop digital input is
removed.
After compressor stop the SSTV valve is kept closed for 60 seconds, not adjustable, and the cooling fan
will have a stop delay of 10 seconds. The stop delay for the cooling fan can be set in the Timers/Motor
fan/Run timer SP menu.
At shutdown the frequency converter is stopped immediately and the SSTV valve is closed immediately.
Vi ratio regulation
UniSAB III regulates the Vi ratio in three steps according to the actual pressure ratio. Before switching
from one Vi step to another, the actual Vi ratio for the compressor must have been present for at least
the time indicated in timer 34 Vi-pause (60 seconds). Otherwise, the change of the Vi step will be
cancelled.
Vi ratio .../Capacity/Vi ratio
Vi low range setting Vi high range setting
Dig. output 12 (Vi)
1.9 2.6
Off
3.2 4.8
On
3.3.25 Oil charging, manually (screw compressors)
Oil cannot be charged when UniSAB III is in Stopped mode. If the compressor is fitted with an oil pump
for oil charging, it can be started the following way: Select Setup/Timers/Oil Charging and the following
picture appears:
Place the cursor on Run timer, press to enter the parameter change field, use and to adjust the
value and press to store the value.
Move the cursor to Start oil pump. Press , select Yes with and press to store the value.
The pump will now start and run for the time set.
For SAB 202, SAB Mk 3 and VMY Mk 3 compressors a Watch the oil pressure alarm will be issued while
the oil pump is in manual operation for oil charging. If the pump should stop before time expiry, select No
under Start oil pump.
Note: As from 2001 SAB 128/163 Mk 3 and SAB 202 are no longer as standard fitted with a valve for ex-
ternal connection to the oil pump suction side. It is therefore not possible to charge oil with the unit oil
pump.
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