4: Display
Amp or kW
The measured signal can be displayed either as ampere or as a kW signal. Select Amp for
Amp signal input. Select kW for kW signal input. The Amp signal can be read as either 0-1 A
or 4-20 mA. Use Motor input signal to choose between the two sources.
5: Motor input signal
0-1 A/4-20 mA
Select 0-1 A when the measured motor current is supplied from a current transformer with
ampere ratio xxx/1 amp connected to the terminals X1/Motor current trafo.
Select 4-20 mA when the measured motor current is supplied from a 4-20 mA transmitter,
e.g. a frequency converter or other equipment. The terminals X1/Motor current are used here.
6: Rotatune
Yes
No
Select Yes if Unisab III is fitted on a compressor with frequency converter. Select No for all
other compressors. For further information, please see Unisab III sequence manual, which de-
scribes the use of frequency converters with Unisab III.
It should be noted that compressors running variable speed (VSD) are at higher risk of facing
vibrational problems than similar fixed speed applications. Johnson Controls Denmark and the
Sabroe factory have gained comprehensive experience in VSD and we are integrating this
knowledge into both the mechanical design and control systems of our products. For this rea-
son we cannot accept liability for any damage related to vibration or variable speed drive on
non-factory built equipment. This includes both mechanical and electrical equipment meaning
that VSD equipment must be purchased as complete factory built and tested packages to en-
sure optimum reliability and to attain full factory warranty coverage. It should be noted that
vibration may appear as structural vibration in frames, piping, instrumentation etc. or as tor-
sional vibration in rotating equipment (compressor shaft, coupling and motor rotor).
Note that for SAB 120, 151, 157HR, 193, 233, 283 and 355 with frequency converter you
must set in a minimum capacity limit when running half speed, i.e. at 1500 rpm or below. The
minimum capacity must be set to:
20 % when 1500 rpm
30 % when 1000 rpm
40 % when 600 rpm
Enter the minimum capacity limit setting in the configuration point Manual zero, see subsec-
tion 6.4.3. Compressor block.
For SAB 120, 151, 157 HR, 193, 233, 283, 355 the configuration of Manual zero is now made
automatically when Rotatune is selected. Based on the setting of Motor RPM min. the value of
Manual zero is calculated to a value, lying within the range 0 to 40%.
Manual zero = (50 - 0.02 x Motor RPM min.) %
Note that for SAB 120, 151, 157HR, 193, 233, 283 and 355 with frequency converter you
may see a problem with low oil pressure at compressor start-up at low rpm.
To avoid this problem a new function Forced speed has been built into the Unisab III code as
from version 1.0.7.0. This function regulates speed up to a predefined value, as long as the
main oil pressure is low. See subsection 6.4.1. Drive - 9: Forced speed for further description.
Up to Unisab III version 1.0.7.0 this problem was handled by an external timer relay connec-
ted to the frequency drive input and a set-up in this frequency converter input which ensured
Set-up
176/319
Engineering manual - Unisab III 1.10
001930 en 2014.09
To Next Page
Loading...
Need help?
General
