Compressor Trip

Why are you sure of no overload?

Low voltage.

Mechanical overloading. (Bad bearings in motor and/or compressor)

Unloader (if equipped) valve circuit not functioning correctly.

If belt driven; belts out of alignment or too tight.

Bad compressor valves.

Clearly you have an electrical overload. The current per phase were once about 50 amperes, they are now 70 amperes. This is the definition of an electrical overload. Since the phase angle of the current changes predominantly with the mechanical load, I suspect that a change in the mechanical load is probably not why the current has dramatically increased. I suspect somewhere some insulation is breaking down or in general another current path has been formed. This might be due to water getting into the wiring system, a capacitor starting to breakdown, crushed wiring, etc.

It would be helpful to know the nominal starting current of this system. If the starting current is normally only 65A (highly unlikely but assumptions must start somewhere) then it is not likely a mechanical loading problem. If the starting current peaks at 600A then mechanical loading and/or too small of a operating current trip has been selected. In the realm of mechanical load changes, you may have a clogged filter, failing bearing, misaligned pulleys, rubbing parts, over pressure, etc.

Hire a competent engineer/technician to examine your system. I cannot see what you have from here.

If the overload device is set correctly either it will be happy at the new current or it will have tripped by now. Your worry indicates that the overload is incorrectly set. Your worry should be that the overload has been set differently to the as-commissioned value.

I would check that the overload is set to the full load current of the equipment as given in your manual first.

What would the consequences be were it to trip?

check for damaged contacts in starter or CB.

Sound like overloading to me. You should ask yourself, What compressor type do i have??? If it a positive displacement then check the pressure to the expected. Then check the compresser curve and estimated power draw should be identified. You might also need to take a flow reading if centriugal compressor.

Ususaly it is the easyer things that go wrong first. Comprssors have a switch that turns the compressor off when it reaches a certain preset or in some cases adjustable pressure setting. Sometimes that is a low and high setting on these switches. But regardless the most common cause is Not overload from mechanical failure of the main compressor although that does happen such as berrings or even a broken Valve spring like on your car engine. But what is most common is the pressure switch that is also sometimes incorrectly called a regulator and most of the time is called the pressure shutoff switch. It is not hard to find and it is not hard to check if that is the problem. IF there is a pressure gage on the system and these should be and IF you know what the pressure is supposed to be and if you have found that the pressure is way up from what it was. Even if it is only 30% more can take 100% more power to get to that higher pressure from the defective pressure shut off switch. You find it connected to the power and to the pipe from the compressor. If adjustable turn it down unless you are sure the pressure in the system is where it normally was. If you find that to be the case then change that switch out for a new one. ASAP. If not that then there are good suggestions about the other likely issues. But this is the most common with compressors. Also Be sure the water drain valve is not stuck. I have in one case hear about a compressor that had a manual water drain valve on the tank only and no one had ever drained it. The compressor tank got so full of water and a little oil from the crank case and the water over time got so much CO2 built up in the system that it caused a problem with the pressure shutoff. In Short. Start with the easy stuff and check and then move on to the next most likely based on the symptoms. So fist thing. Even if there is an automatic water draining system manually drain the water first. Then check the shutoff switch and then check the compressor by removing the belt if belt driven and drain all pressure from the tank and you should be able to turn the compressor by hand if disconnected from the motor and tank. Jim Davison

dear jimmy ,

My salute, i really appreciate for a different approach.

rahul

dear all experts,

Thanks to all for prompt replay. now i am more confident to work on it.

i will get back with reason actually happen soon.

rahul

dear all,

The problem is related with low oil level of compressor.

it is fortunate to correct problems with water drain valve due to forum experts support,

keep in touch thank you all.

Regards

Rahul

To check the components I would first use Ultrasound listening as a matter of fact all your equipment should be trended with ultra sound. Either you have too much load in delivery or something is failing in the compressor or the motor. Infrared inspect all electrical connections and you can also listen with ultrasound for tracking, arcing etc. This should be a basic root cause analysis with the correct equipment.