Hello,
I fitted a H5CN Omron analogue timer in an electrical panel and although everything is working fine now when I had the supply (240V AC) reversed it kept blowing the trip. Can anyone explain why as I thought it did not matter on AC, the timer will operate on AC or DC. I can understand DC needing the correct polarity and I have come across diodes across the supply to check for this, and blowing the trip if connected wrong. If someone could explain in simple terms what electronic set up can cause this I would appreciate it.
Could it be that the neutral terminal is connected to earth internally and putting live on this terminal makes a short? But I thought except for functional earth there should be no connection from live or neutral to earth inside components or appliences or this would effect insulation readings? Thank You

 

According to the spec sheet it does not appear to favour neutral for any particular AC supply terminal?
Max.

 

Check the socket for a connection between pins 10 and 11.

 

my guess is there was a jumper from supply to contacts.

 

Thank you for the replies, as was said there is no preference on AC polarity on the spec sheet and I don't think there was any jumpers but I will check when I go back to work.

Are there any electronic components that could cause the supply trip to blow if the polarity is reversed? (ac)

 

Thank you, are there any electronic components/circuits that would cause a supply to blow if the AC polarity was reversed?

 

Very rare these days, especially for the timer you show in your OP.
Normally any side of the supply terminals would have to be referenced to earth ground for that likely to happen?
Max,

 

Hi, I have checked for any jumpers or links on the socket base and as suspected there wasn't any. As the spec sheet does not specify AC polarity I may contact Omron to see what they say. Its just one of those annoying things I would like to know what could cause it....