Panel control fuse blows

[controlman]

Have you guys come across this type of fault. A 4amp fuse on the secondary side of a transformer blew.
The secondary voltage is 24v, it feeds relays & contactors.Run with no problems for 10years. I monitored the current taken. Always around 2 to 3amps with no peaks. Is it possible for a (gG) fuse to "wear out" as it has been in 10 years. Put new same type fuse in and its running

 

[Hawk81]

i have had the same thing happen a few times. not really what the reason is. i just put it down to the fuse being too long new.

 

[UNG]

Could be one of the contactor coils on it's way out or some dirt on the armature faces causing one contactor to draw slightly more current, is one contactor more noisy than the others?

Only other possibility is ingress of damp into one or more of the contactor coils on initial start fuse blows and clears the moisture fault will not reocur until controls are left idle for a few hours

 

[SirKit Breaker]

Could be the fuse, fair wear and tear, they heat up and cool down a lot in their working lives, sooner or later they will have had enough and just blow.

 

[controlman]

Would you believe it ! Found out there had been an engineer on site repairing the DX cooling unit. He was not allowed to switched off the panel so he disconnected the control cables from the panel. They are 24v and its a functional extra low voltage circuit. He touched the cable to earth OR he reconnected on load (causing spikes). He then said to the client it was co-incidental.