Isolation Transformer

[blacklabs]

We have an isolation transformer that steps down voltage (27kv to 2080v) to power an LCI. It's used to start a gas turbine.
How is an Isolation transformer different?
Thanks
Blacklabs

 

[Skogsgurra]

Different from what? From an auto-transformer?

 

[blacklabs]

Not sure. We have a number of transformers used to step up or step down voltage. None of them were ever referred to as isolation transformers. I can't be more specific at this time.
Thanks

 

[weh3]

What is an LCI?

An "isolation" transformer is usually a 1:1 transformer that is put in either to

1. provide a separately derived system with an isolated ground
2. provide a degree of protection against line transients

However, any two-winding transformer is an isolation transformer because of (1) above, as opposed to an autotransformer.

The only ones I know who ever pushed me to install isolation transformers were a couple of mechanical engineer project managers who had to get a line started up, but the VFD's kept tripping on overvoltage. They had "heard of isolation transformers being used before". I resisted the "temptation" and had the utility take down the secondary taps. I have not heard of any problems, and that was 15 years ago.

Regards,
William

 

[dpc]

Some smaller "isolation" transformers include an electrostatic shield between the primary and secondary windings.

 

[ScottyUK]

LCI is a load-commutated inverter. It is a form of current-source inverter used to drive a synchronous machine. This sounds like it is driving the generator to motor the turbine up to cranking speed. They are usually quite notchy at low speed until the speed picks up and torque pulsations reduce.





----------------------------------

If we learn from our mistakes,
I'm getting a great education!