Stulz C2020 User Manual

EN/07.2013/58/55
4.8.4. Lead lag management
In the system there is always a unit that is the “leader” one: it’s on and the system controls on its probe reading. If
necessary, the leader can ask the support from the other units.
At every interval time, settable by parameter M05, the role of leader is exchanged with that one which has the lower
running hours of evaporator fan. The new leader will be switched on and the old one will be switched off.
Each slave will communicate the running hours of their evaporator fan to the master, which will decide who will switch on.
4.8.5. Cooling without freecooling conditions
The parameters involved are:
• M158 ENABLE DANFOSS COMPRESSOR: pre-set = NO
• M180 OTHER COMPRESSOR START IN SEQUENCING MODE: pre-set = 50 %
If an unit is on and it isn’t sufficient to cool, it will ask support to another unit and the one with lower number of compressor
running hours will be switched on by master. The logic function is under control of the master.
If two units aren’t sufficient to cool, a third one will be switched on following the logic of lower number of compressor
running hours.
For example, in a system of five units the offset is equal to: offset = S06 / (number of unit) = S06 / M04
The compressor is switched on at the temp: The compressor is switched off at the temp:
Unit 1
(Leader board)
T-ON = CS + [B / 5]
T-ON = S01 + [S06 / M04]
T-OFF = CS + [ 0 * B / 5]
T-OFF = S01 + [0 * S06 / M04]
Unit 2 T-ON2 = CS + [2 * B / 5]
T-ON2 = S01 + [2 * S06 / M04]
T-OFF2 = CS + [ 1 * B / 5]
T-OFF2 = S01 + [1 * S06 / M04]
Unit 3 T-ON3 = CS + [3 * B / 5]
T-ON3 = S01 + [3 * S06 / M04]
T-OFF3 = CS + [ 2 * B / 5]
T-OFF3 = S01 + [2 * S06 / M04]
In the next figure there’s an example:
When the Danfoss compressor is enabled (M158 set to YES), it’s possible to set a first step by parameter M180.
In sequencing mode is not possible to select the temperature control mode by parameter M179. The temperature control
is always done by internal temperature.
If there are only three units in the system, the compressor of leader unit will be switched on at temperature:
Temp
Temp set point
1 OFFSET 2 OFFSET 3 OFFSET 4 OFFSET 5 OFFSET
BAND
ON
ON
ON
ON
ON
Leader unit
compressor
Unit 2
compressor
Unit 3
compressor
Unit 4
compressor
Unit 5
compressor
OFF
OFF
OFF
OFF
OFF

Stulz C2020 Specifications

General

Brand	Stulz
Model	C2020
Category	Controller
Language	English