ACRP102 Cooling units Could't backup each other

[BillP]

Hello Dears,

I tried to find a solution to me problem but I couldn't, also Schneider sent an Expert to solve a problem in the Units, but he couldn't to turn the redundancy on.

First of All, the Two units of ACRP102 are in one group connected using two AFC, the connection like this:

Terminator-AC1-AFC-AC2-AFC-Terminator

the two units are of the same FW (6.4.3)

Units Serial Numbers: JK1540003832/ JK1540003831

Model Number: IR25

Controller FW: 6.4.3

I made the configuration for the units typically the same, configured the units As HACS. 

here are the group configuration

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Here are the Group Setpoints

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Here also the ACRP-1 Unit configuration:

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Here are the ACRP-2 Unit Configuration:

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After all these configuration, the two units are in ON Status, not Backup status, and one of the units gives this Alarm: No Backup units available.

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The Other problem, that one of the Units gives Warning : High Humidity Violation, and I set the threshold of the Return Humidity to 90%, but I still have this warning since the reading for the return humidity is 62-82%

what I should do?

Thank you very much

[BillP]

Hello Rami. For the no backups available alarm, you will need to disable the Unit Role Override on the units (under the unit tab under config on the left). This tells the unit to stay cooling and never go into backup. If you want the units to go to backup you will need to disable this command. 

For the humidity alarms, the unit uses the dewpoint to calculate those alarms. The unit uses in HACS, the supply air setpoint (20C) and the return humid threshold (90%) to get the setpoint of 18C. It then uses the return humid (84.5%) the return temperature (23.1C) to calculate the room reading (20C). As the room reading 20C is greater than the setpoint 18C, the unit is alarming on high humid. 84.5% is a very high humidity. Is there a vapor barrier in the room? Is there any humidifier or source of humidity in the room that can be shut off? If the room humidity is 84% a supplemental dehumidifier may need to be brought in to lower the humidity in the room. The units can help dehumidify the room but if it is very humid outside, they will not be able to keep up.

Thank you

[BillP]

Dear Sir,

thank you very much

I will try to make new configuration for the units, and come back to you

[BillP]

Dear Sir,

I disabled the Unit Role Override, one become in ON, and the other in Backup status.

BUT

When the Communication alarm in the on unit occur, the second unit not become on!

I make many tests to confirm that it will run!

it only run when I shutdown the other unit

Could you help me to reduce the humidity using the units set points? not by adding extra devices?

[BillP]

Hello Rami. What is the exact communications alarm that appears when this happens?

Thank you

[BillP]

When I made an alarm on the Unit, the other unit give nothing

BUT

when I shutdown the other unit, the unit running and gives no backup units available 

[BillP]

Hello Rami. When one of the units is turned off in the group I expect the no backups available to come on as the backup unit is no longer going to turn on if something happens to the first unit while turned off. Which alarm were you making on the first unit? Some alarms are just informational which would not kick on the backup unit (ie high rack inlet temp) and others will kick on the backup unit (ie cooling failure).

Thank you

[BillP · Accepted solution]

Dear Sir,

I turned the Driver MCB off, but the second still backup state

[lucasdellasantina]

If you have problem with humidity, you can check the HOT GAS ByPass Valve. check a temperature after and before , both are similar if the valve is have a 30% open or more.