24 volt relays

   / 24 volt relays #1  

bindian

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Wasn't sure where to post this question. I'm installing a 24 volt diverter valve on my CAT E70 excavator. The relay has a "resistor" in it. That's what Amazon called it. I'm not sure which is the ground terminal 85 or 86. I think it is 85. Can anyone tell from looking at this diagram on the relay? CAT 24 Volt Relay.jpg

Here is the tread link if interested..... http://www.tractorbynet.com/forums/hydraulics/348595-caterpillar-diverter-valve.html
hugs, Brandi
 
   / 24 volt relays #2  
its 85 but it really doesn't matter on those it can be 85 or 86 it will work either way the unit has a "diode" not a resistor across the coil the reduce the arch and add longevity to the coil.
 
   / 24 volt relays
  • Thread Starter
#3  
K7LN,
Please take your PM and post it here.
hugs, Brandi
 
   / 24 volt relays
  • Thread Starter
#4  
its 85 but it really doesn't matter on those it can be 85 or 86 it will work either way the unit has a "diode" not a resistor across the coil the reduce the arch and add longevity to the coil.
I don't understand your compounded ran on sentence. Can you restate it?

According to DIN 72552 the coil should be fed with +12V to terminal 86 and grounded via terminal 85, however in practice it makes no difference which way around they are wired, unless you are using a relay with an integrated diode
Automotive Relay Guide | 12 Volt Planet


I now know I have a resistor in my relay, not a diode. I just found the answer to my question here...........Are resistors polarity sensitive?
If I understand your question, then yes - resistors are reversible, in the sense that they can be connected to the circuit in either direction. Resistors are not like diodes or capacitors. They do not have a polarity. The conduct (or resist) current equally in both directions of current flow. Google


So I am sure now ground is terminal 85. Thanks for your help.
hugs, Brandi
 
   / 24 volt relays
  • Thread Starter
#5  
Yes, 85 is the standard DIN relay ground terminal. However, it does matter which way the relay is wired. If it's wired with pin 86 as ground, the protective diode will conduct and the coil will not get energized. Also, there must be a "resistor" in the relay if it is not made with a 24 volt coil. The resistor is there to drop the 24 volts to the proper level to operate the coil. If a diode were used instead of a resistor, the diode would only drop .7 of a volt and not the 12 volts that we assume would be required to operate a 12 volt DC coil.

Correct, resistors have no polarity.

Thanks.
hugs, Brandi
 
 
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