Substation DC problem

The negative pole of the 60VDC battery bank keeps going greenish. l mean the terminal changes from its silverish color to greenish after a period and the connecting cable to the rectifier also becomes wet. This happens to only the main negative terminal. I guess some chemistry is going on. Any solutions?

You have some electrolyte leakage around the pole and it's reacting with the metal. The seal is often broken when someone gets too enthusiastic with a wrench tightening terminals. Test with litmus. not knowing what chemistry your battery uses makes it hard to predict the reaction, but this is extremely common with lead acid batteries because the terminations are soft lead and stressing them loosens them because lead doesn't spring back from deflection.

Regards
cww

Petroleum jelly is your best friend around lead acid batteries, smear that over all the terminals and you won't have to worry again.

Roy