Short pilot light
Short pilot light
(OP)
Has anyone encountered problem due to a short pilot light? What could be the cause of this?
The application is the following: 24 VDC pilot light (ABB model CBK-KLF8G) turned on by proximity switch Turck BI3U-M12-AP6X-H1141 (3-wire device). Wired in parallel with this pilot light, I have a PLC input. Lately, when the prox would turn on, the PLC wouldn't get the input from the prox, which LED, in turn, was not ON.
After some troubleshooting from maintenance personel, I learned that apparently, the pilot light was short, thus sucking the current that would normally have turned ON my input. By replacing it, it worked. Is this a problem that could have been avoided at first by an LED instead of the pilot light? by putting a resistor in series with the light?
Thx
The application is the following: 24 VDC pilot light (ABB model CBK-KLF8G) turned on by proximity switch Turck BI3U-M12-AP6X-H1141 (3-wire device). Wired in parallel with this pilot light, I have a PLC input. Lately, when the prox would turn on, the PLC wouldn't get the input from the prox, which LED, in turn, was not ON.
After some troubleshooting from maintenance personel, I learned that apparently, the pilot light was short, thus sucking the current that would normally have turned ON my input. By replacing it, it worked. Is this a problem that could have been avoided at first by an LED instead of the pilot light? by putting a resistor in series with the light?
Thx





RE: Short pilot light
Light bulbs more often fail open circuit. LEDs and resistors would fail much less often than would a light bulb.
These are the sorts of decisions that can give safety engineers grey hair.
RE: Short pilot light
RE: Short pilot light
There are also prox's that have an LED built-in, if you absolutely need a visual for troubleshooting.
Wm
RE: Short pilot light
The LED replacements aren't inexpensice, but I have used them to replace indicator lamps on transmitters, specially those in remote sites which get only a quarterly check-up. It is good to walk into the transmitter building and see the proper indicators glowing (or the fault indicators glowing...you at least know where the problem lies).
I remain,
The Old Soldering Gunslinger