Current sensing of a low voltage surgical lighting system

[dgreeley6]

We are trying to sense current (proxy for occupancy) of a Stryker low voltage surgical lighting system. The lighting control panel has no status output, totally encased cable from panel to light, and an incoming line voltage feed. Any ideas on HOW we could determine the light is "on" by CT or other method?
Thanks in advance.

 

[GoldDigger]

Similar circuit to what is used in a power strip that senses current in the computer receptacle and cuts off other receptacles for accessories.
Not quite sure how they do that though.
You would need some sort of active circuitry, since you could not pull much power from a CT.

Tapatalk!

 

[just the cowboy]

Maybe some thing like this
http://nktechnologies.com/current-indicators/ampflasher-current-indicator.html

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[Jraef]

Maybe some thing like this
http://nktechnologies.com/current-indicators/ampflasher-current-indicator.html

​

+1 on the NK Technologies product, nice stuff, I've used them often (but they are local boys to me, so I like to support them). You will see the same NK units brand labeled by several other people when you start looking, if they are blue, they are NK.

Another alternative is Veris Industries in Oregon, also good stuff.

 

[steve66]

I'm not sure how you would use one of those to sense current on a totally enclosed cable without breaking the cable open and cutting one lead to pass it through the sensor.

I wouldn't want to do that to an OR light.

 

[GoldDigger]

We are trying to sense current (proxy for occupancy) of a Stryker low voltage surgical lighting system. The lighting control panel has no status output, totally encased cable from panel to light, and an incoming line voltage feed. Any ideas on HOW we could determine the light is "on" by CT or other method?
Thanks in advance.

What sort of indication do you need? Relay contact? Visual indicator?
Controlling other lighting or letting the security guard know the room is in use?


Tapatalk!

 

[Jraef]

Duplicate post deleted

 

[Jraef]

I'm not sure how you would use one of those to sense current on a totally enclosed cable without breaking the cable open and cutting one lead to pass it through the sensor.

I wouldn't want to do that to an OR light.

Both companies offer a split core version that you open up, place around the conductor, and re-close. You would have to place it in an area where the cable, if sheathed, comes out of the sheath to terminate onto something.
View attachment 10067

 

[GoldDigger]

I'm not sure how you would use one of those to sense current on a totally enclosed cable without breaking the cable open and cutting one lead to pass it through the sensor.

I wouldn't want to do that to an OR light.

You said that the cable from the control panel to the light is sealed, but that just means that the sensor would have to be placed on the AC input to the panel.
It would have to have a threshold between the light-on and light-off input current values to the panel.

Tapatalk!

 

[dgreeley6]

Thanks for your reply...good idea, we will try this!

 

[steve66]

You said that the cable from the control panel to the light is sealed, but that just means that the sensor would have to be placed on the AC input to the panel.
It would have to have a threshold between the light-on and light-off input current values to the panel.

Tapatalk!

Yes, that would work, and its much better than messing with the low voltage cable.

I guess that is what everyone else was thinking anyway, but for some reason, the title of the post made me think he was trying to put something on the low voltage side.