Hello ALL,

I am using a micro PLC to operate one 24VDC and one AC motor using 24VDC/10Amp relays (all relays are activated using 24VDC), DC motor drives constant load and has a brake while AC motor drives variable load. DC motor runs for about 5 seconds and then stops and brake is applied, after DC motor has stopped AC motor runs for 2 minutes, stops deactivates the DC brake and then DC motor rotates in opposite direction and comes back to its original position,

Brake is connected to seperate relay but is activated and deactivated using AC motor signal, means same o/p operates AC motor and DC brake.(this is because I do not have enough outputs)

The problem is when AC motor is driving low load, everything works fine, but when AC motor is driving heavey load, DC motor does not come back to its original position, it tries to but 6.3Amp fuse connected to DC power supply blows, means it tries to draw too much current,

Does this has to do anything with AC motor relay being operated for long time?? and AC motor driving heavey loads or the brake not being deactivated, by looking at the relay I can say that break relay is switching off,

But weird thing is that this only happens when heavey load is driven by AC motor, when light weight is driven all works OK,

I hope I have explained it clearly, if someone with experience could please suggest about relays, or what can I do to change things. Has someone else experienced something like this?

any thoughts, views ?

I would appreciate any suggestions

regards
Kaz