45kw motor and generator problem

[Rocboni]

Trouble is it's £250 to find out.

 

[westward10]

Think you need to explain to the owner this and that there is no guarantees it will resolve it. Why did they replace the old generator.

 

[Rocboni]

I will do, this is a vast improvement in terms of protection on the usual set up, the sockets are usually straight onto the bus bars of the generators and the older ones don't have RCDs built in! So this is all quite hard to explain and hard to get them to understand why you need all this.

They will also want suggestions how to overcome this but there's space to fit a Mccb.

How would you normally supply this size of motor?

 

[westward10]

BS88 fuses or a suitable mccb.

 

[Rocboni]

The motor is actually supplied buy 2x 100 A and an 80amp bs88 fuses (not ideal) before the star/delta contractors and these are holding up, by the looks of it the 80amp is an original.

 

[westward10]

The mcb I feel is the Achilles heel as they are not suitable for large size motor protection.

 

[Cadgey123]

The motor is actually supplied buy 2x 100 A and an 80amp bs88 fuses (not ideal) before the star/delta contractors and these are holding up, by the looks of it the 80amp is an original.

Link the MCB out the equation to see what happens?...

You said you had added protection in regards to the other fuses.

 

[Rocboni]

They have fitted a 4 pole isolator at the moment so that can operate, but ther is no protection for the cable and socket other than the MCcb in the generator with is about 400Amps

 

[westward10]

Link the MCB out the equation to see what happens?...

You said you had added protection in regards to the other fuses.

Link out the mcb is just removing the problem not solving it plus you remove circuit protection for the socket.

 

[davesparks]

what is the overload trip on the starter doing during all of this? Assuming it is set correctly then that should be providing the overload protection so the mcb or whatever will only be needed for fault protection.

 

[westward10]

The relay would be more tolerant to current peaks whereas the mcb is not and that is the problem. The same goes for the BS88 fuses.

 

[Dozer 73]

A handy little tool for selecting gen set sizes etc
Macfarlane Generators Power Calculator - https://www.macfarlanegenerators.com.au/power-calculator.php

 

[Dozer 73]

A handy little tool for selecting gen set sizes etc
Macfarlane Generators Power Calculator - https://www.macfarlanegenerators.com.au/power-calculator.php

Know it's the the solution to your post , just a good tool to have

 

[Rocboni]

I turned the changeover time up to 10 seconds and it's been fine ever since however I have ordered a D type so will fit that for piece of mind.

 

[westward10]

That is what I suggested way back in #6, glad it seems to have resolved it.