Thermocold Quattro 2550Z Chiller

[nzchillers]

Anyone working on Thermocold’s Quattro series of heat recovery chillers.

We are having issues with the system tripping on “hp thermal overload alarm” translated loss of power on carel pco b digital over load. The wring is connected in series through the mech hp cond fan thermal overloads and motor protection relays.

So far we have logged the system with Testo gauges and verified the charge and setup of the thermostatic expansion valves (R407c S/H 6 dew S/C 4 bubble).

The system has been isolated on chiller + recovery and recovery only to allow the system to run on cooling only to fault find.

We have swapped over the motor protection relays pco b relay board and inspected wiring to eliminate intermittent faults. The cond fans are controlled via 0 – 10v signal to inverter modules and conrol well.

The compressors have been meggared and monitored during running (discharge temp 69 – 72˚C, run amps and motor resistance measured 300 - 320ohms) motor protection module trips at 450ohms. Compressors are Copeland scroll ZR310.

We have bridged out the cond thermal overloads, and have tried to isolating one comp at a time. The system runs any where from 1 – 13 hours and trips there are no patterns available.

The compressor oil levels are ok. All solenoid coils and valves appear to be operating ok.

We have had a lot of problems with these chillers in New Zealand !

[nzchillers]

Typo

We are having issues with the system tripping on “hp thermal overload alarm” translated loss of power on carel pco b digital in put




Anyone working on Thermocold’s Quattro series of heat recovery chillers.

We are having issues with the system tripping on “hp thermal overload alarm” translated loss of power on carel pco b digital over load. The wring is connected in series through the mech hp cond fan thermal overloads and motor protection relays.

So far we have logged the system with Testo gauges and verified the charge and setup of the thermostatic expansion valves (R407c S/H 6 dew S/C 4 bubble).

The system has been isolated on chiller + recovery and recovery only to allow the system to run on cooling only to fault find.

We have swapped over the motor protection relays pco b relay board and inspected wiring to eliminate intermittent faults. The cond fans are controlled via 0 – 10v signal to inverter modules and conrol well.

The compressors have been meggared and monitored during running (discharge temp 69 – 72˚C, run amps and motor resistance measured 300 - 320ohms) motor protection module trips at 450ohms. Compressors are Copeland scroll ZR310.

We have bridged out the cond thermal overloads, and have tried to isolating one comp at a time. The system runs any where from 1 – 13 hours and trips there are no patterns available.

The compressor oil levels are ok. All solenoid coils and valves appear to be operating ok.

We have had a lot of problems with these chillers in New Zealand !

[D.Evans]

Hi nzchillers
As someone who has worked on plenty of Thermocold chillers and heatpumps I believe the electrical circuit you are referring to is the 240vac supply through the high motor temperature modules, condenser fan thermal overloads and high pressure switches. This circuit goes to one of the C number digital inputs on the PCO board and is switched by the board to output on the corresponding NO terminal on the PCO board that controls the compressor contactors. If one of the switches goes open circuit the alarm given is misleading and the way I have found which determines which one of the switches has gone open circuit is to fit latching relays to various points along the chain so that the relay that drops out is where the circuit has gone open. Hope this helps.

[NoNickName]

Still I don't understand which of the contact opens. fans? compressors? overloads?

[nike123]

Still I don't understand which of the contact opens. fans? compressors? overloads?

I suppose they are all connected in series to digital input of Carel pCO configured as "high pressure/thermal overload alarm" and therefore could not be immediately said what protection has acted. If Hp switch is manual reset type than it can be excluded. Also, if compressor thermal overload is set to manual reset, than it is obvious that fan overload is one, what makes this tripping.

[NoNickName]

Ok, they are in series. Still: if they are not MR, which one opens? Unless serious troubleshooting is done, we can't help.

[nike123]

Yep, I agree!

[nike123]

We have bridged out the cond thermal overloads, and have tried to isolating one comp at a time. The system runs any where from 1 – 13 hours and trips there are no patterns available.


Do you have some time (2-5sec.) programed in pCO for intermittent error prevention of that alarm? Maybe some contacts are lose or exposed to vibrations etc.

[Garrett12]

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