EN - 54
When the time delay has elapsed:
a) If the first fan stage is turned on, standard control is resumed.
b) If the first fan stage is not turned on, the 90-second time delay is repeated.
Standard control is resumed at the end of the time delay.
During this 3 minute period, the control has priority over any stop requests and the protections remain on.
After running for 1 minute:
- The compressor continues adjusting if the pressure difference (HP-LP) is greater than 1 bar.
- The compressor is turned off if the pressure difference (HP-LP) is less than 1 bar (lubrication fault).
After running for 8 minutes:
- The compressor continues adjusting if the pressure difference (HP-LP) is greater than 3 bar.
- If the pressure difference (HP-LP) is lower than 3 bar, the compressor is forced to operate at full capacity (100%) until the 10th minute elapses
(up to 4 bar).
After running for 10 minutes:
- The compressor continues adjusting if the pressure difference (HP-LP) is greater than 3 bar.
- The compressor is turned off if the pressure difference (HP-LP) is less than 3 bar (lubrication fault).
21. LIMIT MANAGEMENT
These limitations are used to reduce the capacity of the compressors to prevent their safety devices tripping when the machine nears its
operating limits.
High pressure operation:
If the condensing pressure is greater than the control HP limit (P54), Xtraconnect 2 forces the compressor to lower its capacity while running.
When the high pressure drops to below 98% of P54, the HP limitation remains on but the compressor is not requested to do anything (intake
and exhaust valves left closed).
The high pressure limit is disabled when the high pressure drops to below 90% of P54.
Message displayed:
Water freeze limit:
If the water temperature drops below the freeze limit (P52) + 2°C, Xtraconnect 2 forces the compressor to lower its capacity while running.
This freeze limit is disabled when the water temperature rises above P52 + 3.5°C.
Message displayed:
Evaporator freeze limit
P70: ∆T between the antifreeze water temperature and the evaporating temperature (compressor suction saturation). P70 = 6°C by default if
P52 ≥ 2 or P70 = 8 if P52 < 2 and adjustable between 0 to 10 (resolution: 0.5)
This control is enabled 2 minutes after the compressor is turned on.
P70 message:
● If the saturation temperature on the evaporator outlet drops below P52 – P70, the control will lower the compressor's output. If, after two
minutes, the saturation temperature remains below P52 – P70, the circuit is turned off by its protection device.
Display:
- If the saturation temperature on the evaporator outlet rises to an allowable value, the compressor is authorised in increase its capacity.
Power input limitation
- This function is accessible only if the optional DIRIS energy meter is installed on the machine and parameter P117 is set to Yes.
This limitation can be activated at all times or it can activated by an on/off input (terminals 8-9 on terminal block J3 on the ADD3 board) or over a
Bus, but always in relation to parameters P118.1 and P118.2 (adjustable over a Bus).
When the machine's total power input exceeds the set threshold for 10 seconds and at least two compressors are running, the controller opens
the exhaust valve on one of the compressors. If the total power input does not fall below the threshold after 60 seconds, the exhaust valves on
the other compressors are opened in turn until a maximum of three compressors are running at minimum capacity.
If this does not work, the compressors are turned off in turn. However, one compressor must be kept running.
- In order for a compressor to start up again or its intake valve to open, the power input must be less than P118.1 – P118.2 and the outdoor or
water inlet temperature (depending on the unit type) must be less 1°C lower than that stored in memory when the compressor was load-shed.
HP LIMIT CIRCUIT
X IN PART LOAD
WATER FREEZE LIMIT
UNIT IN PART LOAD
P70 ANTIFREEZE DIFF
LP/EVAP T x.x°
CX EVAP T./FREEZE LIM.
UNIT IN PART LOAD
P118.1 MAXIMUM POWER
LEVEL xxxKW
P118.2 DIFFERENCE FROM
MAX POWER xxxKW
To Next Page
Loading...