halfcan
10-04-2017, 08:00 AM
Hi,
I look after a chiller that is comprised of two circuits, each with one hitachi screw compressor.
One of the circuits will run for hours and hours, but eventually trip out and 'comp thermal trip' is displayed on the digital interface. I've proved that it's definitely the klixon breaking to bring this error up, however I haven't witnessed it cutting out with my own eyes, I'll leave it, go and do something else, check it now and then, and sometimes it can take up to a whole day to cutout. It seems to run as well as the other circuit. Here are some circuit readings from both.
Condenser coils are clean.
Compressor 1 (no problems)
Ref - R407C
Evap pressure - 4.5 BarG
Evap temp - 5°C (approx)
Suction pipe temp - 12°C
Superheat - 7K
Entering water temp - (between 12-15°C fluctuating)
Leaving water temp - 6°C (this is setpoint - and therefore operation stops when this is satisfied).
Condensing pressure - 14.5 BarG
Cond. temp - 40°C
Discharge pipe temp - 60°
Liquid line pipe temp - 30°C
Subcooling - 30K
De-superheating - 30K
Compressor running amps - approx 20-21A
1kV winding resistance check
U to V - over 1000 Giga ohms
V to W - over 1000 Giga ohms
U to W - over 1000 Giga ohms
Earth insulation check
U to earth - 800 + mega ohms
V to earth - 800 + mega ohms
W to earth - 800 + mega ohms
Compressor 2 (thermal trip error)
Ref - R407C
Evap pressure - 4.5 BarG
Evap temp - 5°C (approx)
Suction pipe temp - 12°C
Superheat - 7K
Entering water temp - (between 12-15°C fluctuating)
Leaving water temp - 6°C (this is setpoint - and therefore operation stops when this is satisfied).
Condensing pressure - 14.5 BarG
Cond. temp - 40°C
Discharge pipe temp - 60°
Liquid line pipe temp - 30°C
Subcooling - 30K
De-superheating - 30K
Compressor running amps - approx 24-29A
1kV to earth resistance check
U to V - not going over 300 mega ohms
V to W - over 1000 MEGA ohms
U to W - over 1000 MEGA ohms
U to earth - around 280 mega ohms
V to earth - 800 + mega ohms
W to earth - around 500 mega ohms
Operation wise it seems ok, therefore I'm thinking it's likely I've got an issue with the windings on compressor two.
Thoughts??
Any checks you suggest I should carry out?
Thank you
I look after a chiller that is comprised of two circuits, each with one hitachi screw compressor.
One of the circuits will run for hours and hours, but eventually trip out and 'comp thermal trip' is displayed on the digital interface. I've proved that it's definitely the klixon breaking to bring this error up, however I haven't witnessed it cutting out with my own eyes, I'll leave it, go and do something else, check it now and then, and sometimes it can take up to a whole day to cutout. It seems to run as well as the other circuit. Here are some circuit readings from both.
Condenser coils are clean.
Compressor 1 (no problems)
Ref - R407C
Evap pressure - 4.5 BarG
Evap temp - 5°C (approx)
Suction pipe temp - 12°C
Superheat - 7K
Entering water temp - (between 12-15°C fluctuating)
Leaving water temp - 6°C (this is setpoint - and therefore operation stops when this is satisfied).
Condensing pressure - 14.5 BarG
Cond. temp - 40°C
Discharge pipe temp - 60°
Liquid line pipe temp - 30°C
Subcooling - 30K
De-superheating - 30K
Compressor running amps - approx 20-21A
1kV winding resistance check
U to V - over 1000 Giga ohms
V to W - over 1000 Giga ohms
U to W - over 1000 Giga ohms
Earth insulation check
U to earth - 800 + mega ohms
V to earth - 800 + mega ohms
W to earth - 800 + mega ohms
Compressor 2 (thermal trip error)
Ref - R407C
Evap pressure - 4.5 BarG
Evap temp - 5°C (approx)
Suction pipe temp - 12°C
Superheat - 7K
Entering water temp - (between 12-15°C fluctuating)
Leaving water temp - 6°C (this is setpoint - and therefore operation stops when this is satisfied).
Condensing pressure - 14.5 BarG
Cond. temp - 40°C
Discharge pipe temp - 60°
Liquid line pipe temp - 30°C
Subcooling - 30K
De-superheating - 30K
Compressor running amps - approx 24-29A
1kV to earth resistance check
U to V - not going over 300 mega ohms
V to W - over 1000 MEGA ohms
U to W - over 1000 MEGA ohms
U to earth - around 280 mega ohms
V to earth - 800 + mega ohms
W to earth - around 500 mega ohms
Operation wise it seems ok, therefore I'm thinking it's likely I've got an issue with the windings on compressor two.
Thoughts??
Any checks you suggest I should carry out?
Thank you