ISSUE REF – ART234
There was an issue recently were the Relay 86EA tripped and would not reset. Quite often it is not obvious what causes the trip of the 86 Protection Relays, as they can have multiple inputs that can trip it. It is worth looking at the display to see what alarms are showing as often this will give you valuable information. In this case there was a general alarm for the vibration system, as well as the alarm for 86EA.
On the photo you can see the warning lights as they are before startup. Two of the Bypass warning lights are active which is normal. These will clear once the turbine is started. The card indicated by the red arrow is the relay card. On a SwitfPak three of the four channels used. One will trip side A, one will trip Side B and one will trip the Unit (both turbines). If you have a vibration issue on the generator for example you need to trip both turbines.
The arrow is pointing at the OK light of the relay module. This green light was not present, so there was an issue with the card.
The screws indicated in green were loosened to replace the Relay Card with a good one. This had no effect, there wasn’t any change – the OK light was still not lighting up.
At the back of the chassis there is also a card associated with the relay module. It is directly behind the front card. In the photo you can see the three channels that connect to the CPU. You can also see the multi pin connectors connecting the back card with the chassis.
On the left photo you can see some of the eight relays marked by yellow arrow.
On the righ photo you can see where the four channels are attached to the CPU.
We removed the cover of the module and it had a burnt out resistor.
Replaced the aft card and the system was back to normal.
End of article