I have this circuit and the signal lamp always burns with two or three months of use, does anyone know why?

 

What kind of lamp is it - incandescent, led, or...
What is it's rated voltage and what voltage are you applying to it?

 

Without further information, at a guess, I would say you need a fly back diode on the relay coil.

 

Without further information, at a guess, I would say you need a fly back diode on the relay coil.

Yes, if it is an LED. No, if it is incandescent.

 

Yes, if it is an LED. No, if it is incandescent.

If it is a poorly chosen incandescent, the back EMF pulse could kill it as the filament weakens.

 

I would say back emf from the relay K1 is causing the bulb to blow, try using a Neon .

 

I would say back emf from the relay K1 is causing the bulb to blow, try using a Neon .

A neon is no use at 24V.

 

If a flyback diode does not solve the problem, replace the lamp with a LED and suitable series resistor.

 

A neon is no use at 24V.

Where does it say he's using 24V?

The drawing shows L & N.. which suggests that the voltage 120/230AC.

 

Where does it say he's using 24V?

The drawing shows L & N.. which suggests that the voltage 120/230AC.

His second, attached schematic shows +24V with similar circuit. So which is it, 24V or Line voltages? Hence the ambiguity in the question.

 

If it is the 24vdc circuit, most indicators are now LED and are very reliable, it shows simple contact closure with no Inductor in the circuit.
If the AC version, If there is a spare contact switch it separately, or place an R/C snubber across the coil.

 

K1 appears to be the contactor coil so it has quite a large coil which should have a R/C snubber an any case.