an undesirable power consumption if the Vi slide valve is activated immediately. Therefore,
the capacity slide is moved as quickly as possible down into the area where Unisab III calcu-
lates that the power consumption will be reasonable. After this, Unisab III will move on to
points 2 and 3.
3.9.5 Change to part load
When changing from full load to part load, Unisab III will run through the following steps:
1. If necessary, move capacity slide (and Vi slide) as close as possible to the limit Vi
mode to avoid undesirable capacity jumps. However, stop movement if/when reaching
the limit for reasonable power consumption.
2. Deactivate solenoid valve of Vi slide to release Vi slide and move it to minimum posi-
tion.
3. If still necessary, move capacity slide to the limit Vi mode.
4. Change to normal capacity control.
3.9.6 Position indications
In the picture Control values/Capacity/Values, capacity and Vi slide position are indicated. At
full load Capacity will show 100% while Vi slide position is calculated from the actual capacity
slide position. At part load Capacity will show the actual capacity slide position while Vi slide
position is 0%.
3.9.7 Slide brake control
The slide brake is released for a short time (Brake delay) before the slide motor is activated.
The brake is also released for this period of time (Brake delay) after deactivating the slide
motor. Brake delay can be selected within the range 0 to 0.5 seconds in the picture Service/
Diagnose/Software/Misc Functions.
3.9.8 Capacity shutdown
If the slide does not move as expected a capacity shutdown will be issued. This means that
every time the slide moves at least 0.5% in the chosen direction a Capacity timer is reset to
100 seconds. If it is expected to move, the timer will count down. If the timer reaches 0, the
alarm will be issued. Inspect the timer in the picture Service/Diagnose/Software/Misc Func-
tions.
Compressor control and surveillance
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Engineering manual - Unisab III 1.10
001930 en 2014.09
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