Pointeggs
06-01-2014, 07:56 PM
Hey everyone, happy new years!! Greetings all the way from Namibia
This is my first post, so be gentle :) and feel free to correct me if needed.
I was recently called out to this reefer. On arrival I found the compressor to be overheated and tripped on its internal clixon.
The reefer alarm code was al82 "Compressor head over temperature"
The compressor is a Copeland scroll R-404 with a damaged nameplate so I don't know the model number
I cleared the alarm list and shut down the unit to let the compressor cool down.
Upon starting the unit I measured the voltages at the compressor terminals all 380Volts between phases and 220Volts to neutral.
The compressor was making a lot of noise and started to heat up really fast - so I shut down the unit again. Upon consulting a colleague I changed the phase rotation at the power supply. After letting the compressor cool down I restarted the unit and observed it for about 1/2 hour. It did not overheat anymore. Suction pressure 200kpa High side pressure 2200kpa. Ambient temp 37 deg. C The reefer was standing in a shaded area.
4 days later the compressor overheated again. A new reefer was put next to this one and the power leads from the supply board was switched. So I changed the phase rotation again and the unit ran fine.
A colleague of mine told me my changing of the phase rotation was not needed as this unit will not allow the compressor to run with the wrong phase rotation. Instead I should have checked the operation of the modulating valve.
The reefer has since been emptied and sent back by ship so I don't know of its status now.
I was unable to inspect the unit from the inside as it was a public holiday and it was sealed awaiting customs clearance.
Please note this was only my second encounter with a reefer unit - yes I am a reefer newbie.
Question 1:
-------------
Is this unit not supposed to identify the phase rotation and select the correct one? Or is it possible that this can malfunction?
Question 2:
-------------
What exactly does the modulating valve do and which other component/sensor actuates it? How do I fault find this part?
Thanks in advance
This is my first post, so be gentle :) and feel free to correct me if needed.
I was recently called out to this reefer. On arrival I found the compressor to be overheated and tripped on its internal clixon.
The reefer alarm code was al82 "Compressor head over temperature"
The compressor is a Copeland scroll R-404 with a damaged nameplate so I don't know the model number
I cleared the alarm list and shut down the unit to let the compressor cool down.
Upon starting the unit I measured the voltages at the compressor terminals all 380Volts between phases and 220Volts to neutral.
The compressor was making a lot of noise and started to heat up really fast - so I shut down the unit again. Upon consulting a colleague I changed the phase rotation at the power supply. After letting the compressor cool down I restarted the unit and observed it for about 1/2 hour. It did not overheat anymore. Suction pressure 200kpa High side pressure 2200kpa. Ambient temp 37 deg. C The reefer was standing in a shaded area.
4 days later the compressor overheated again. A new reefer was put next to this one and the power leads from the supply board was switched. So I changed the phase rotation again and the unit ran fine.
A colleague of mine told me my changing of the phase rotation was not needed as this unit will not allow the compressor to run with the wrong phase rotation. Instead I should have checked the operation of the modulating valve.
The reefer has since been emptied and sent back by ship so I don't know of its status now.
I was unable to inspect the unit from the inside as it was a public holiday and it was sealed awaiting customs clearance.
Please note this was only my second encounter with a reefer unit - yes I am a reefer newbie.
Question 1:
-------------
Is this unit not supposed to identify the phase rotation and select the correct one? Or is it possible that this can malfunction?
Question 2:
-------------
What exactly does the modulating valve do and which other component/sensor actuates it? How do I fault find this part?
Thanks in advance