Thread: Can somebody decypher this relay for me?

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I've searched high and low for a better explanation of what's what, but here it is:



Your guidance is much appreciated

Ok looks like 2 and 10 are your coil (where power comes in)

8-11 and 4-1 are normally closed contacts and 11-9 and 1-3 are normally open.

Not exacly sure about 5,6,and 7. It looks like a switch, or it could be another normally open/closed contact. I am probably off completely on this. It looks like it is a base layout for an ice cube relay and those things have always thrown me off

That's exactly what it is. Based on other answers elsewhere, it sounds like you're on the mark with 5, 6 and 7 being a third open/closed contact.

My hope is to use this in my MIB. It's a 10A 120V relay. The idea is to have a motion sensor trip the relay which would then power up the motor. The motor however draws 4.2A and I'm pretty sure it'd burn out the sensor if wired directly via an outlet.

Think this will do the job?

And if so, anybody have any thoughts on how best to wire it?

If I were doing it I would use one of the cheap motion sensor lights from wally world, remove the sockets and tie the wiring from the socket to the coil on the relay. You could have the motion relay on test or with a motor in the works I would put it on a 1 or 2 minute run.

I think you are right that the motor draw would fry the relay in the motion sensor, 4.2 amps at 120Vac is a little over 500 Watts. I would guess that most sensors would not last long beyond 1 amp or 150 Watts.

You are exactly right in wanting to use this relay to switch on a motor of that size.

The diagram you presented is a socket diagram. The relay sits in a socket like the ones used for old radio tubes. The socket is keyed at the top so the relay can only go in one way.

Pins 5 and 6 are a set of normally closed contacts while 6 and 7 are a set of normally open. That is for sure. All the rest has been accurately described above.

I frequently have used relays with high amperage contacts to do the dirty work for circuits designed to switch lower powered things. That is the way to go.

Here's the only problem.

You will need a way to lock the relay on for a certain period of time. You don't want someone to set off the effect, have it run for a second, and then shut off because the person ran out of range. You need it to stay on for a period of time that seems reasonable once it is tripped whether someone is still in the beam or not.

A lockout period is also a good idea so the effect does not run continuously if you have a line of people walking by.

I know they sell timers that do just what I am describing, but I will try to think of another way on the cheap to get it done.

Originally Posted by HalloweenBob

Here's the only problem.

You will need a way to lock the relay on for a certain period of time.A lockout period is also a good idea so the effect does not run continuously if you have a line of people walking by.

Yeah, I know what you're saying. The sensor does have a couple of "knobs" on the bottom that i'm assuming are for this very thing. Sets how long the light comes on. The other most likely adjusts sensitivity. If I can get it in the right place with the sensitivity crnaked it will hopefully remain triggered while they are in "sight" of the sensor.

Anyway, I've got time to play with it and tweak things.


Actually... this is your relay and motor. I'm giving the coffin a mind of it's own so to speak.

What type of motor are you using? Some motors have a FLA (Full Load Amperage) starting current draw of 400 - 600 TIMES the running current!!!


Modifying a PIR light is probably your best idea. They are EASILY modified, we can remove the internal wiring and wire them to a larger relay for your purpose.

There are however "timer" relays on the market. For a basic one you'd be looking at at least 50dollars. This would allow you to control one of the following functions; time on, delay on or delay off. These relays work well if your limited for space. or need a multitude of functions!

As for your diagram, this is one of many standard relays available. Complete with 3 contacts, each available for use as NO (Normally Open) , NC (Normally Closed) or BOTH!

Wiring this device is simple

2 - 10 : Trigger device, mat switch, PIR. Just remember it acts like a switch as well. You need power on this circuit, whatever voltage your coil is rated for.

1 - 3 : Your motor. Connect the incoming power to terminal 1. 3 goes to your motor power and then returns back through a return, also known as a neutral back to your power source


Also note: If you buy a base for this relay the numbering system on the base may not be identical to that of the relay! Yes you heard me! There is no standard on these relays! Most of them DO follow this system but they don't have to ! So just do a little continuity testing before you assume anything or you may end up with dead shorts and a blown relay

Thanks everybopdy for the plethora of info! All very helpful!

Now, crypt Keeper, let's see if I can run down your post...

The motor, I'm not certain. What I can tell you is that it's a 1/6 HP motor, draw is listed as 4.2A, if that helps.

As for the PIR, I had one laying around that I'm hoping to use. I assume it once went to a porch light that no longer exists. My predecessor left the sensor behind so I'm giving it a new purpose. If it doesn't work out, then it's offf to Home Depot for the cheap $12 one I saw to replace it.

And the NO/NC thing is indeed cool. This means I can have 1-2 things going on on the normally closed contacts then have them turn off and switch to the coffin rattling it's cover. Perhaps somehting along the lines of having the ambient lights turn off so they focus their attention on the coffin. Just an example, I may or may not ever use the extra contacts. But I like the potential they offer. And it has a base that is marked accordingly and matches the relay. So that's nice.

So, the motion sensor... I'm using the standard automatic light sensor. 3 wires. Red, black, and in this case brown not white. i'm not sure how that will work out so that Home depot trip may be in order.

But let's go with your standard 3 wire motion sensor for outdoor lights. How would you suggest hooking this up to the coil? The coil, as far as I can see and have read, is set up for 110VAC.

In most cases this is how these devices are wired

Black - 110volt Constant Power
Brown- Neutral
Red - Switched Power


Therefore....Power goes to your black wire and turns on or off your red wire

So...

Blackwire to power source (black)
Red wire to coil (2)
Coil (10) to neutral (brown) and neutral from power source (white)

You might want to confirm that the brown wire is indeed the neutral. I will assume it is by process of elimination and a bit of a experience. Sometimes manufactures get away with using odd color wires because they sell them as "units" not meant to be dismantled by others.


Do you know what the contacts on that specific relay are good for? Do you have model number for the relay? Manufacturer Etc? I can probably dig up the data sheet with HP ratings and direct current ratings.

ok, pulling this from memory, so I may be slightly off but here goes...

the relay is a Potter & Brumfield KRPA-14AG-120

I'm about 90% sure that's right.