a question about relays

Dear colleagues

somtimes happens we have no rapid access to an AC relay but DC relays with similiar pins and contact arrangments are available.

the question is that how can we replace a faulty or burnt AC relay with a DC relay or vise versa ?

and what is the difference in the make up and construction of AC and DC relays?

Just apply a bridge rectifier (without capacitor!) for coil, it will work.
The DC relay contains only the coil on the core, an AC relay contain an additional "loop" on the core. The loop work as "secondary winding" when the supply voltage AC.
The AC relay work fine with 50...60% DC of original voltage.