Magnetic Safety Switch for X-ray Generator

Support Q&A
1

Hi,

I’m looking to purchase a non-contact switch that can function as an external interlock for an X-ray generator. The switch will be mounted in the door of a lead-shielded cabinet that will have an X-ray generator on top. How I want this to work is: when the door is closed, the interlock circuit is closed, and it’s safe to energize the X-ray generator. If the door is accidentally opened, the interlock circuit opens, and power to the X-ray generator is cut.

The generator has two pins devoted to connect a safety switch. These two pins are labeled as follows (see chart below):

Pin 11: Interlock Return Input: Connect to Pin 12 to close Interlock

Pint 12: Interlock Output: +15 Vdc @open, 5 mA when connected to pin 11

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Two things are unclear to me:

  1. Most switches operated at 12 or 24 Vdc but the voltage supplied by the X-ray generator is just 15 Vdc. Is this a problem? Which voltage should I look for?

  2. The switch must have 2 wires. However, there are two contact configurations that I found: 2 NO and 1 NC + 1 NO. My understanding is that the configuration I need for the switch to operate in the way I want is the latter.

Are there any magnetic switches that can be wired to this generator?

Thanks in advance!

Fred

2

Hello Fred,

Would something like part number 1738-SEN0387-ND work for you?

3

Greetings,

What I’d take that to mean is that the switch needs to be capable of tolerating 15V when open, carrying/switching a 5 mA load when closed, and be of a a single-pole, normally open type that simply connects the two wires together when your door is closed.

Such things are very common, with several hundred items of the basic form listed here, and this other family containing packaged magnets for use with many of the same.

Be advised that these are basic component products, rather than formal Safety items. If you’re in the sort of environment that insists on the latter, that’d be an entirely different product family with 2-3 additional digits on the price tag.

4

Hi Rick and Rob,

Thanks for your replies. I believe your suggestions would work. However, I’m looking for something that’s (i) a little more involved in terms of must release distance (ideally less than 10 mm), and (ii) the sensor and the magnet come together. Ideally, it’d have a LED indicator (but this is not a must).

I was looking at something like this:

However, this is a a NO/NC contact configuration. Would this work for my application? Thanks again!

Fred

5

As a reference, the more industrial type safety related non-contact switches can be found here, and yes, they are significantly more expensive.

Note that some of these use RFID rather than magnetic detection, which eliminates the risk of another magnet “tricking” the sensor into thinking it was closed when it wasn’t.

Also, many of these have a second switch for redundancy, which is important in many high-risk type applications.