I normally blog on the radio control sites however I need help with an electrical issue so here I am.

I have been using a 240V fridge compressor to generate vacuum for a vacuum bag setup used to laminate model aircraft wings. Rather than run the motor for the 12 or more hours require for the epoxy to set, I have purchased a vacuum switch.

For the switch to operator the motor I was advised to include a relay, which I have now purchased.

Now I need a wiring diagram.


Specifications:
The motor currently has earth neutral and active

The vacuum switch is produced by switching solutions and is a SVA/SVF vacuum switch. Its a 4 pin switch earth and 1, 2 and 3, switching from 2 to 3.

The relay is an Idec RH2b-UL on an SH2B-05C base, and is an 8 pin.

With the switch installed the motor will cut out once the desired level of vacuum is achieved and restart when the level of vacuum drops.

I am hoping that the wiring of these three can be suggested.

 

Could you mention the whole partnumber of the relay?

RH2b-UL-????

 

Thanks for the reply.

The number provided is the full part number. I did have a look when I was making my investigations and found it on the manufacturers /or suppliers site in a data sheet (PDF). Its made by Idec, who appear to be quite prolific.

 

Some of the RH2b-UL series relays have coils needing 120V. Others work on 12V or 24V. Since the part number is incomplete, there is no way to know which relay you have, and no way to know how to hook it up.

Perhaps the vendor who provided the relay will have additional information.

 

You can tell what the voltage rating of the coil is by it's resistance.
Here are some of the part numbers vs the resistance of the coils:
RH2b-ULAC110-120V -- 4170 Ohms
RH2b-ULAC24V -------- 153 Ohms
RH2b-ULDC100-110V - 12100 Ohms
RH2b-ULDC24V -------- 650 Ohms
RH2b-ULDC12V -------- 160 Ohms

Why don't you measure your coil and report back as to it's resistance?

 

Thanks thingmaker, I do like the comment ;
"Just because two things can be connected together does not mean that they should be connected together." - D.R.

sgtWoookie further scrutiny of the case indicates the following details;

The relay is ac 220-2240v rated at 50-60hz. It is rated at 7a at 240v general use. The 240v being for Australian application. Sorry about the rating being expressed in lower case. The shift key on this board does not work. Typing this on Microsoft word at least gives me capitals where required.

Hope this is sufficient information. If not I can do further testing once I get home later in the day.

 

There is a 240V version also:

http://www.idec.com/language/english/brochure/Relay_20Selection_20guide.pdf

 

Have a look at the attached schematic.

Now, the bottom of your relay has 8 connectors on it. There are two off by themselves on one side. These are for the coil. The others are in two groups of three. It's easier to just make a simple graphic:

X1  a1 C1 b1
I    I  I  I
I    I  I  I
X2  a2 C2 b2

X1 and X2 are the two ends of the relay coil.
C1 is the common for one side of the relay, C2 is the common for the other side of the relay.
I don't know offhand which is the NO and which is the NC side, which is why those contacts are labeled "aN" and "bN", N=1 or 2.

You wire 220v to both of the NO sides, and the motor hot/live side to the two common terminals. Using both relay switch contacts will make it last much longer than if you only used one set of contacts.

Note that on the vacuum switch, I assumed you meant that the normally closed contacts are pins 2 and 3.

 

Back to my computer where all the buttons work.

Thanks for the guidance on this.
SgtWookie the diagram now that I see it, makes sense. I like the idea of using both sides of the relay so it lasts longer, will definitely do that.

Hope to have it all together tonight. Will take some photos of the setup and post them once it’s complete.


Regards Jaison.