Electrical Question

It burnt out!

Broken?

Fuse blown?

It is only a coil without iron core.

Your English is not clear and precise. So I am not certain what problem you are having. Please clarify what you are doing, especially if none of my guesses are correct.

You may have an under sized 24VDC power supply. If the 24VAC coil is rated to draw 0.5A with a 24VAC source, when a 24VDC is applied the current draw will be considerably higher because the coil inductance will not limit the current. If this current level exceeds the capability of your supply that you sized based on the AC current rating then the supply will protect itself and shut down.

You may not have just an AC coil. This package (relay?) may have a DC blocking capacitor in series with the coil to prevent DC current from leaving a residual magnetic field in the core.

You may even be trying to detect the magnetic field improperly.

AC and DC don't mix well....

24v AC is about 34v peak to peak, thus 24v DC may not be giving sufficient voltage to operate whatever it is you are trying to energize.
Del

Its not peak to peak but peak voltage. In AC voltage across inductor is I.XL where XL= 2.pie.f.L

'Peak' and 'peak to peak' are both perfectly valid measurements.
Anyhow, it's doesn't matter a jot what you call it.
The fact of the matter is the wobbleosity of 24vAC gives more thrunge than 24v DC
Del