Johnson Controls SABROE Unisab III Control, Engineering Manual

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Engineering manual - UniSAB III 1.10.8
146/346
001930 en 2021.06
Compressor control and surveillance
Alarm and shutdown supervision settings are made in the picture Control values/Process temp/Process
in temp/Limits . This function is enabled in Set up/Configuration/Plant/Proces in temp . Monitoring is al-
ways active.
3.6.3 Oil return from oil separator (ChillPAC)
When the compressor starts running, the Oil return delay timer is started. When this timer runs out, the
oil return valve is open for the time set in the Oil return open timer. Then the valve is closed for the time
set in the Oil return close timer. Once again the valve is open for the time set in the Oil return open timer,
etc.
If the Oil return close timer is set to 1 second, and the Oil return open timer is set to 600 seconds, this
function will work like the existing Oil return function for a reciprocating compressor.
This function is enabled in Set up/Configuration/Plant/Oil return sep. It is active when the compressor is
running, i.e. when there is feedback from the motor starter.
Note: For ChillPAC Mk 3 units, the Oil return close timer is set to 1 second, and the Oil return open timer
is set to 600 seconds.
3.6.4 Oil return from evaporator (ChillPAC/PAC)
The two oil return valves controlled will open when the evaporator level switch gets high and be kept
open until a few seconds after the signal from the switch gets low again. This close delay time is set in
the
Oil return evap. timer. The level switch is a float indicator in a vessel under the evaporator.
This function is enabled in Set up/Configuration/plant/Oil return evap. It is active when the compressor is
running, i.e. when there is feedback from the motor starter.
3.6.5 By-pass function (ChillPAC)
During start-up the by-pass valve must be open for a few seconds. The open time is set in the By-pass
start timer.
This function is enabled in Set up/Configuration/plant/By-pass start . It is active when the compressor is
running, i.e. when there is feedback from the motor starter.
3.6.6 Flow evaporator (ChillPAC/PAC)
A shutdown No evaporator flow is given after a short delay when there is no flow through the evaporator,
i. e. no signal from the evaporator flow switch. The shutdown delay time is set in the Flow evaporator
timer.
This function is enabled in Set up/Configuration/Plant/Flow evap. It is active when the compressor is
running, i.e. when the evaporator pump is started.
3.6.7 Flow condenser (ChillPAC/PAC - optional)
A shutdown No condenser flow is given after a short delay when there is no flow through the condenser,
i. e. no signal from the condenser flow switch. The shutdown delay time is set in the Flow condenser
timer.
This function is enabled in Set up/Configuration/Plant/Flow cond. It is active when the compressor is
running, i.e. the condenser pump is started.
3.6.8 Liquid level limiter (ChillPAC)
The limiter will reduce compressor capacity as long as the liquid level is high in the evaporator.
For fixed speed compressors, it will reduce capacity with up to 33-50% (disengage one or more steps)
and the
Delay down timer is active.