Neutral Displacement Relay Fault

Isn't it time the original equipment manufacturer's local technical representative was called in to help?

I believe neutral displacement relay will show as 59BN on your protection single line. If I was listening, when it was explained to me, it protects your neutral free bus, between your generator breaker ( synchronising breaker ) & your generator transformer, from earth faults, prior to synchronism, after which you have a neutral, at the generator, & neutral associated protection to take over for earth fault protection. The relay does some clever Maths, to calculate a theoretical rise of neutral potential, due to fault. The VT used may show an open delta connection arrangement. The delta is open at one corner. I would start by checking VTs, or VT secondary fuses / mcbs, though your relays may already cover this as a separate VT fuse fail function. Hope this helps, Colintonybone