Wiring a relay for 220 VAC (Europe)

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fncruz

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Location
New Providence, NJ
Hi,

I am used to working on electrical enclosures in the US and need help wiring a relay for a valve to be used in Europe. In the US I have the HOT wire (120 VAC) going to one side of the contact. The other side of the contact goes to my valve. I also have a Neutral wire going to the valve. See picture below.

Relay.JPG
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In Europe there is no Neutral. Instead there are two HOT wires correct?

Does this mean that I need the neutral wire going to the valve to also be on a relay? If not then I would always have 120 VAC, via the second HOT wire, going to the valve.

Thanks.

FC
 
Smart $

Smart $

Esteemed Member
Location
Ohio
jumper said:
I understand what you mean in context, but the term "voltage rail" is unfamiliar.
Click to expand...
In his diagram, the vertical lines on the left and right are "rails". I believe it stems from being called a ladder diagram and the main support members to each side of a real ladder being called rails... and I assume that stems from a ladder appearing much like railroad tracks. Sheer speculation on my part. :happyyes:
 
jumper

jumper

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3 Hr 2 Min from Winged Horses
Smart $ said:
In his diagram, the vertical lines on the left and right are "rails". I believe it stems from being called a ladder diagram and the main support members to each side of a real ladder being called rails... and I assume that stems from a ladder appearing much like railroad tracks. Sheer speculation on my part. :happyyes:
Click to expand...

Ah the schematic/ladder diagram.:slaphead:

My brain was on a wye tranny and thinking "what darn rails is he talking about?".
 
Jraef

Jraef

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Electrical Engineer
Ladder diagram. On a ladder, the sides are rails, the cross connections are rungs, both terms are used in electrical ladder diagrams. In railroad tracks you have side by side rails too, but the cross connections are ties.

Besides, calling something a "railroad track diagram" would be awfully confusing...

Back to the OP's issue; I've found that the confusion over here about single phase circuits used overseas is in it being 230V, which for US is line-to-line, so people here assume when they see 230V* that's how it will be. But for them, 230V is line-to-neutral, and it's correct that they don't really use 120V for controls, unless forced into it by some North American OEM that doesn't bother to check first. Then they hate you because replacement parts are harder to get over there.

Best bet if you are making equipment for export, use 24VDC for controls, then use an auto-ranging DC power supply connected to the AC line so that no matter where it is connected, the controls are always the same.

*Side note: 220, 230, 240V, it's all nominal. Some countries are still 380Y220, some are 400Y230, some are still 415Y240. The "harmonized" official level is now 400Y230V so that everyone else is nominally within acceptable tolerances.
 
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Smart $

Smart $

Esteemed Member
Location
Ohio
Jraef said:
Ladder diagram. On a ladder, the sides are rails, the cross connections are rungs, both terms are used in electrical ladder diagrams. In railroad tracks you have side by side rails too, but the cross connections are ties.

Besides, calling something a "railroad track diagram" would be awfully confusing...
Click to expand...
;)

I was just speculating that the sides of ladders got the "rail" moniker from being similar to railroad tracks. Perhaps it was the other way around as I assume ladders were invented and in use long before railroad tracks. Did not mean to suggest changing anything.
 
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winnie

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Location
Springfield, MA, USA
Occupation
Electric motor research
My understanding for European _appliances_ or equipment that gets plugged in:
While the electrical system will be 230V 'hot to neutral', the connection plug will not be polarized and both sides must be treated as 'hot' and thus switched.

-Jon
 
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winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Tony, we are talking about machine control, not appliances. I brought in the side topic as potentially relevant in that in many cases in Europe you will have a power supply which is 'hot to grounded conductor' but where you can't depend upon knowing which conductor is grounded.

In a situation where you don't know which supply conductor is grounded, you need to design your system as if either or both conductor may be 'hot'.

-Jon
 
Besoeker

Besoeker

Senior Member
Location
UK
Smart $ said:
That’s news to me.

Would the [solenoid?] valve circuit depicted in OP be considered control or power in UK/EU?
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Tony is right.
Industrial controls are very often 110Vac derived from a local control transformer and/or 24Vdc wich is becoming more widespread particularly in conjunction with PLCs.

This is a typical VSD control panel wiring:

TypicalVSD01_zpscd13bf34.jpg


The structure of the ladder diagram is clearly evident.
 
Smart $

Smart $

Esteemed Member
Location
Ohio
Besoeker said:
...
The structure of the ladder diagram is clearly evident.
Click to expand...
Yeah, but what is it with these image posts that are so smalle that the text cannot be discerned. In your image, it's gonna take a pretty good pair of eyes to pick the control transformer. May as well forget reading any of the annotations. :blink:
 
Besoeker

Besoeker

Senior Member
Location
UK
Smart $ said:
Yeah, but what is it with these image posts that are so smalle that the text cannot be discerned. In your image, it's gonna take a pretty good pair of eyes to pick the control transformer. May as well forget reading any of the annotations. :blink:
Click to expand...
The 110Vac control transformer is in the top left hand corner below the three phase supply. In normal operation, it is fed from the load side of the main isolator. There is an alternative feed from the live side of the isolator which permits control circuit testing without the power being applied to the VSD. It's a feature commonly in the spec for petrochem applications.
 
Besoeker

Besoeker

Senior Member
Location
UK
winnie said:
My understanding for European _appliances_ or equipment that gets plugged in:
While the electrical system will be 230V 'hot to neutral', the connection plug will not be polarized and both sides must be treated as 'hot' and thus switched.

-Jon
Click to expand...
The connection plug will go in only one way.

Plugandsocket_zps6344f5f5.jpg
 
Besoeker

Besoeker

Senior Member
Location
UK
Smart $ said:
Yes but of the hot and neutral, which is which. I'm assuming the wide, long blade is ground.
Click to expand...
As you look at the slots, the vertical is earth. Live is to the right and neutral to the left.
You can't put the plug in wrong polarity.
And the live side has an in line cartridge fuse, max 13A.
Most appliances these days come with a pre-wired moulded plug.
 
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