Electrical isolation required for mechanical work?

Mechanical repairs required to a 3 MW, 11 KV standby generator engine. Then genset also operates on a triad system. The control side will be isolated to ensure that the prime mover does not start during repairs. Is there a need for electrical isolation of the HV alternator & busbar breaker during repairs? No work will be carried out on the electrical side. TIA

Reply to
BIGEYE
Loading thread data ...

Wow! The potential for a disaster here is enormous! I can't recommend strongly enough that you have a competent high voltage electrician, and/or an electrical engineer evaluate your installation, and the purposed work before you commence!

Your company, and/or the facility where the work is to be performed should have an effective and clearly defined high voltage safety procedure in place for work of this nature before a cover screw is removed. Things such as racking out switches (not just turning off and locking out), and the installation of bonding straps between the phase conductors and ground, multiple locks (one for each individual involved in the process) to be installed and removed only by the person placing it, working in teams with a clear chain of command, will be considered and implemented as required.

This is one area where redundancy, and pre work planning is good. You might not get a second chance!

Louis

Reply to
Louis Bybee

He's talking about some mechanics working on the engine, not the HV generator.

The control circuits should be locked out. The starting mechanism (something this size is probably started with compressed air) should be isolated and locked out. Maybe even the fuel supply should be isolated Don't trust just the control circuit to not start the unit.. And I would have the output breaker open, racked out and locked to prevent accidental closure motorizing the unit.

If no one is opening any generator components, the big concern is rolling the engine over while someone has their hands in it. The generator covers and wiring are not to be touched in any way. If the work will be extensive or dusty, cover the generator ventilation with canvas or plastic to prevent dust getting into unit.

daestrom

Reply to
daestrom

Aside from the 11kV, put a Tweco welding-cable connector in the negative starter-battery lead for any non-running work on the genset.

--s falke

Reply to
s falke

Thanks guys for your replies. Although no work will be done on the HV system, electrically it will be made safe with carefully thought out switching schedule. It was the mechanical side I was not sure about. But you have put my mind at ease with your suggestions.

Reply to
BIGEYE

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.