cranes for electric post
I have encountered a problem. This 30 ton crane wasn't able to pickup the load of greater than 18ton of weight. A 16 sqr.mm, 4 core cable was available as a spare. So this cable was used, you can see the old arrangement as in this picture.Unfortunately, I took the picture late, it has been opened up and wires have got free.
It was opened up and the cable was doubled, new picture is not shown, crane was then able to pickup the mechanical load of 18 ton easily.Just imagine a right breaker having 6 cables attach to 3 poles of breakers. Two RED,Two Yellow,Two Green.
Things that I observed.
The current capacity of that cable per core, accroding to catalog of cable=79A
The current reading through clamp meter per core=132A
STILL THE CIRCUIT BREAKER OF 100A DIDN'T TRIP
By doubling the cable 79x2=158A, per phase crane will get 158A.
Things that are still on my wind
1)Why the breaker of 100A didn't trip at readings of 100A,132A?
2)Why the crane didn't pickup the load when cable was single?
As a side effect, it should have got heaten up, but it must support currents of 100A.A cable that has maximum current per core=79A, why wasn't it able to flow up more than 79A at a cost of it's depriciation/destruction. I used to think before, that if i allow more current from 79A to let it flow, it will self destroy itself, but will allow to carry the current. But what I observed was that this crane wasn't able to pickup heavy load, as you can see in the picture.
The Electrical Over head crane is not able to lift this piece of steel on a single cable and the hoist motor(the top motor, that picks up load) was producing a great hum.When cable was doubled, crane operators said in the following words, it appears as if this crane has got a new life and it's more quick and powerful than before.