Why breaker didn't trip:

[cabel_2000]

I work in maintenance for a major chemical company. We had a water softener line break above a compressor. The disconnect for the compressor was filled up with water. (There is a window in the front of disconnect) We could see the water boiling inside the disconnect until we shut off the power. How did this not trip anything?

 

[Megawatt]

I work in maintenance for a major chemical company. We had a water softener line break above a compressor. The disconnect for the compressor was filled up with water. (There is a window in the front of disconnect) We could see the water boiling inside the disconnect until we shut off the power. How did this not trip anything?

The only reason I know of is the plant you are talking about has a 480vac or 600vac delta 3 phase system which means you don’t have a neutral at the sub station.It is possible for a phase to go to ground and not trip a breaker or blow a fuse. I’ve worked in many delta wired plants which have 3 lights with 1 light for each phase and if 1 light doesn’t light up and the other 2 get brighter then you have a ground somewhere in the plant and everything seems to be running normal. I can’t explain the theory behind a delta wired system but from experience I know that a phase can go to ground and not trip a breaker. We have a member named @Lucien Nunes that could explain this system better than I can. Good luck

 

[Megawatt]

I work in maintenance for a major chemical company. We had a water softener line break above a compressor. The disconnect for the compressor was filled up with water. (There is a window in the front of disconnect) We could see the water boiling inside the disconnect until we shut off the power. How did this not trip anything?

The reason I think this is that it doesn’t have a neutral for faults to return to the system to actually trip breakers or blow fuses. Again I can’t give you a good reason for your problem. I would really like to see what @Lucien Nunes has to say

 

[James]

A compressor is normally quite a large load.
water is not a great conductor so the current may well have been below the fuse rating of whatever supply’s that disconnector.

 

[Megawatt]

A compressor is normally quite a large load.
water is not a great conductor so the current may well have been below the fuse rating of whatever supply’s that disconnector.

I would have to say that the compressor is being fed from a motor control center which is the line voltage with no neutral. If someone sets a large transformer and is delta wired on the primary and WYE on the secondary to feed the compressor and then if this situation happens then it would trip the breaker.

 

[James]

Why?
electricity won’t care if it is star or delta, with or without N
if the box is full of water, current will flow from phase to phase and be roughly balanced.
depending on the resistance of the water the current flowing may not be huge.
if there is an rcd (ground fault detector) then it is likely to trip out but if you are relying on over current, it may take a long time for the water to become either conductive enough to raise the current for the breaker to trip

the other thing that may happen with time, water may boil off and the steaming atmosphere inside the box may ionise and an arc could pass direct from phase to phase or phase to ground.

 

[Lucien Nunes]

As per @James it's likely that the current flowing through the water was within the normal range of currents for the compressor circuit and no overload actually happened.

You didn't mention the voltage or the size of breakers / fuses. But consider a regular domestic 120V kettle with a 1500W element and how fast that boils water. 1500W is only 1.8A on a 480/277V 3-phase circuit. If you had say a 50A circuit and the compressor was using 40A, the breaker will give you at least another 25A without tripping, which corresponds to the boiling power of 14 kettles.

Electrode boilers that heat water or produce steam by passing current through it have been around nearly as long as ones with heating elements. They have drawbacks and complications but are very compact and fast to respond. They have been made in all sizes from an over-sink unit of 1-2kW up to 100MW running on 36kV.