Grounding in ships
Grounding in ships
(OP)
Dear Folks,
In one of the ships, all 3-ph AC generator neutrals (9NO.,) are solidly connected to Ship hull. Pl. suggest me, is it require to calculate Touch and step potential?
Generator rating:
110kVA, 415V AC 3ph, 60Hz
Advanced thanks
Rajesh.T
In one of the ships, all 3-ph AC generator neutrals (9NO.,) are solidly connected to Ship hull. Pl. suggest me, is it require to calculate Touch and step potential?
Generator rating:
110kVA, 415V AC 3ph, 60Hz
Advanced thanks
Rajesh.T





RE: Grounding in ships
respectfully
RE: Grounding in ships
Is it require / possible to calculate Step/touch potentials of the ship?
RE: Grounding in ships
Please select forums carefully.
RE: Grounding in ships
Here you esentially have an infinte conducting plane which in analogy to the substation, you are stting on a large big conducting plate.
In esence, and with the fault current you can encounter and assuming the groundig conductors are relatively large, I see no need for any calcs of step and touch potential.
You have the best groudnging field you can have.
JIM
RE: Grounding in ships
RE: Grounding in ships
RE: Grounding in ships
Given that iron oxides usually form on the support rails for machinery after a few years and grounding of machinery through the base may not be dependable, I suggest grounding all large machinery with a separate copper conductor. A calculation based on the impedance of the supply conductors and the grounding conductor should give you a worst case touch voltage after several years of service.
respectfully
RE: Grounding in ships
Basically this is a Barge mounted desalination plant. It is not for sail.This barge contain 9-AC generator sets and all neutrals are solidly connected to ship hull without neutral breaking during parallel operation.
Mr.rovineye: All generator neutrals have individual neutral O/C relays. If any spl.protection needed for this application, pl. advice me. Advanced thanks
RE: Grounding in ships
I use a high resistance ground on the switchboard bus to monitor and LIMIT ground faults, and where I have large motors isolated from that bus we use neutral earthing resistors connected at the star point to limit voltage and current during ground fault. But we are at much higher voltages.
Ships 4160v and below I have always seen and used completely ungrounded installations. Ground monitors are required then, not to limit ground faults but to prevent them. Superimposed DC or ground detection transformers are typicaly used, both sending a signal to notify that one phase is grounded and you better fix it before another grounds and causes a bolted fault.
I guess I still don't understand the reason for the Y ground on a 415 volt vessel when you are not using the star connection for distribution.