Two power supplies configured +15V and -15V output (BOOOM) ???

[RHeTTRoNiCS]

Hello...my machine got power supply faulty. This power supply have two output voltages. The +15V and the -15V with 18A current. I don't have spare for this type of power supply but I have two separate power supplies with +15V output 30A. Now to up my machine I had configured these two power supplies to get +15V and -15V power source. I connected the negative terminal of power supply "A" to the positive terminal of power supply "B". So I got 3 terminals on the output as below:

+15V = the positive terminal of the power supply "A"
Comm = the connection between neg of power supply "A" and pos of power supply "B".
-15V = the negative terminal of the power supply "B".

Now it looks fine when I power up manually...I could get the output +15V and -15V with common reference. The problem is when we installed it on the machine and power-up....multiple fuse blown from the PCB (not from power supplies). I don't exactly what went wrong...but I don't know...Any idea guys? thanks a lot.

 

[esp1]

hi,
Are the 15V at 30A power supplies, Earth free, ie: both the Positive and Negative outputs isolated from Ground/Chassis.??

E

 

[RHeTTRoNiCS]

hi,
Are the 15V at 30A power supplies, Earth free, ie: both the Positive and Negative outputs isolated from Ground/Chassis.??

E

Yes..both output terminals (pos and neg) from power supplies are isolated from Chassis gnd.

 

[RHeTTRoNiCS]

By the way the jumper between two supplies i connected to chassis ground...AC input is also isolated from chassis ground...So it Should be fine right? But why it blown the fuses and broke 3 pcbs....huh!