fail-safe electrical indicator

[DanielG]

We've got some equipment that gets attached to a larger machine intermittently, which it's attached, they SHOULD hook up a cable, bug it's possible that they won't. I want on indicator on the removable part that shows if the cable hasn't been hooked up correctly. That is, it needs to indicate red when there isn't power. Possible options might be:

1) A red indicator held out by a spring, when the cable is connected, an electromagnet pulls it in.
2) Electrochromic glass covering a red panel. The glass is clear when there's no power, so the red is visible.

I'd like something off the shelf, but haven't seen anything. Does anyone know of a product that would work?

 

[Strostkovy]

Use a rotary solenoid with a colored wheel. They turn 90 degrees when power is applied and spring back to 0 when power is lost.

 

[Tony Quiring]

What is in the cable signal wise?

If you have power and ground then you can use a simple SPDP relay and wire coil to the power with correct coil voltage then via a separate power supply connect to the Common and Normally Closed contacts so when cord connected relay activates breaking the C to NC connection.

Unplug cord and power goes away, relay relaxes and C is connected to NC resulting in power applied to indicating device.

If cable only has safety ground or referenceground and logic signals then you can assume once connected both parts will have common voltage and can do same thing with the relay except using the ground from connector to drive the relay.

Remember to add diode to relaycil to reduce bounce spike.

You could use the relay to interface with the start button or contactor to interlock the machine so it cannot start unless connected.

Easy to do depending on what is in the cable.

Sent from my SM-G781V using Tapatalk

 

[Strostkovy]

Rotary solenoid returns very few results. Rotary electromagnet is what you should search

 

[DanielG]

Rotary solenoid returns very few results. Rotary electromagnet is what you should search

That would work great. I didn't know rotary solenoids existed. I've only seen the linear kind.