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| Identify value in ohms relative of coil relay |
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| Jasonbit:
Hello folks, I need know how many resistance the coil of 40.31 relay finder has. Because I am calculating the schematic where I will use a simply transistor PNP to control this relay. I am trying identify the value in ohm relative to the coil of the relay. I am search around on the web and I found this article: https://na.industrial.panasonic.com/blog/how-measure-contact-resistance-relays After I read the article (my level english it is not very good) but I don't understand how this test works. Because when I turn on the coil and the contacts close my power supply 6VDC/1A will short circuit, right? Anyway, how can I identify the value of this coil (in ohm's)? I use the test diode of multimeter (like this image: https://snag.gy/3lFeEU.jpg). My multimeter shows the value 81 in display. The unit of this value is ohms? Datasheet: https://docs-emea.rs-online.com/webdocs/138b/0900766b8138ba16.pdf Thanks |
| PTR_1275:
That document you linked to is measuring contact resistance not coil resistance What relay are you using? Do you have a data sheet? |
| Jasonbit:
--- Quote from: PTR_1275 on November 08, 2018, 11:58:29 am ---That document you linked to is measuring contact resistance not coil resistance What relay are you using? Do you have a data sheet? --- End quote --- But how can I measuring contact resistance? You're going to short-circuit, right? I intend using this relay: 40.31 https://docs-emea.rs-online.com/webdocs/138b/0900766b8138ba16.pdf Thanks |
| PTR_1275:
One way of measuring low resistances is with a known current (say 1.0000A) and measuring the voltage drop between 2 points. You may think it’s shorted, but if it’s 10mOhm, you will see 10mV across the contacts (at 1.0000A) The data sheet gives lots of info and variables on the coil. What voltage are you running the relay from? The data sheet says 0.65 watts for dc operation. That gives a current of ~54mA and should have a resistance of around 200ohms. This would be measurable with the normal ohms range on a multimeter. Keep in mind the tolerances will vary that figure. |
| Jasonbit:
--- Quote from: PTR_1275 on November 08, 2018, 12:42:33 pm ---One way of measuring low resistances is with a known current (say 1.0000A) and measuring the voltage drop between 2 points. You may think it’s shorted, but if it’s 10mOhm, you will see 10mV across the contacts (at 1.0000A) The data sheet gives lots of info and variables on the coil. What voltage are you running the relay from? The data sheet says 0.65 watts for dc operation. That gives a current of ~54mA and should have a resistance of around 200ohms. This would be measurable with the normal ohms range on a multimeter. Keep in mind the tolerances will vary that figure. --- End quote --- Thanks to your reply, I will study and do again this steps in laboratory. I will share the results in this thread. Thanks |
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