Hooking up Amp meter to Baldor 220v single phase motor

clockworkman said:

Hello
I am looking for some help on how to connect a amp meter to a 220 volt Baldor single phase motor. The incoming power only has a black, red, and green wire, there is no neutral. I assume the coil of the amp meter goes around the navy blue wire that leads to the motor but I'm not sure which wires to hook up to the two terminals on the amp meter.

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I'm a bit confused what you're on about?.

In the distant past in the UK (and much of the world) the standard colours were green for earth, red for live, and black for neutral - they were altered long ago, due to concerns over colour blindness. But there's still a LOT of green/red/black out there.

Assuming the three wires going out the bottom conduit on the last picture are to the motor, then the green is obviously earth, as it connects to an earth point on the box. Red will be live, and black will be neutral, standard old colours.

I've no idea what you mean by "goes around", an ammeter goes in series with the lead - so you would disconnect either red (live) or black (neutral) and insert the meter in the break - it makes no difference which you use, as live and neutral are exactly the same for most purposes. To satisfy my mild OCD tenancies, I'd generally use the red wire unless there was some specific reason to use the black (like there was already a convenient break in the black wire).

As you're presumably in the USA, with their strange dual-phase system, then for a 220V motor you don't actually use the mains 'neutral', you connect directly across the two lives - so one of the lives effectively becomes the 'neutral' as far as the motor is concerned.

There's nothing 'special' about live and neutral, they are mostly arbitrary terms - unlike DC where positive and negative are very important.

If you were in most of the rest of the world, you might be using a three phase motor, which can have three wires (L1, L2, L3) or four wires (L1, L2, L3 and Neutral), depending on the configuration, Delta or Star.

I too am confused by your question. You connect the ammeter in series with either one of the supply leads. (This is for an ammeter with two terminals.) When you say "the coil of the ammeter" do you mean the toroidal current transformer that you thread one of the supply conductors through ? (If it is a clip on ammeter then the part that you clip around the conducter is effectivly a current transformer.
In the USA and Canada the secondary of the final transformer in the distribution system is a 220 volt winding with a center tap. The center tap is neutral and is normally connected to earth at the transformer. There may be a small voltage between neutral and earth where the supply enters your house due to the voltage drop due to current flowing through the neutral conductor. You do not get a shock if you touch the neutral. If you touch either of the live conducters you will get a 110 volt shock. (This is assuming that you are nominaly at earth potential.)
It is different in the UK and Europe where the final distribution transformer is a thee phase transformer. The star point is neutral. You house will be fed with live from one of the there phases plus neutral and earth. Groups of houses are distributed between the three phases tomtry to balance the load between the three phases. If you touch live with this system you wil get a 240 volt shock.
I do not agree with Nigel that neutral is arbitary. It is the conductor that is nominaly at ground potential.

Les.

Yes, the coil I am referring to is the indictive ring .my understanding is both the red and black wires are hot.

Also, if I wire in series...if the ammeter fails so will the motor, correct?

clockworkman said:

Also, if I wire in series...if the ammeter fails so will the motor, correct?

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Yes, but it's a very unlikely occurrence, but using a current transformer round one of the wires (either one) will prevent that - effectively a 'clamp on' meter.

Here it is in more detail. So you're saying red incoming wire into one terminal and then connect the other terminal to the motor, correct?

In a 230v system the grounded neutral is identical to the live conductor as far as inserting a in-series amp-meter.
So you should see the same reading regardless which conductor.
IOW, both conductors are identical, just that one is referenced to earth GND.
In N.A. the 240v system is supplied from the 'outer' ends of a a 120v-0v-120v 1ph transformer.
Again, this meter can go in either lead,
The Chinese origin meter you show, indicates the non-invasive method of reading by virtue of the ferrous pick-up? i.e, the ring around the conductor,
You need to confirm this, is there a sheet with the meter?
In the pic above, you show the ferrite ring!

MaxHeadRoom78 said:

In a 230v system the grounded neutral is identical to the live conductor as far as inserting a in-series amp-meter.
So you should see the same reading regardless which conductor.
IOW, both conductors are identical, just that one is referenced to earth GND.
In N.A. the 240v system is supplied from the 'outer' ends of a a 120v-0v-120v 1ph transformer.
Again, this meter can go in either lead,
The Chinese origin meter you show, indicates the non-invasive method of reading by virtue of the ferrous pick-up? i.e, the ring around the conductor,
You need to confirm this, is there a sheet with the meter?
In the pic above, you show the ferrite ring!

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Yes, I am wondering how to supply power to the led readout itself. Which wires to connect to the 2 terminals at the bottom

I think you need to give us some details of the ammeter. I was asuming it was a analogue meter with either two terminals on the back that actualy measured the current passing between the two terminal OR it used a current transformer with the winding connected to the meter. To use the type with a current transformer you just thread ONE (NOT BOTH.) of the live wires through the hole in the current transformer. The black ring in the middle od you hand is a current transformer.
What is the green and white thing with two screw connections in the same picture ?
Les.

Les Jones said:

I think you need to give us some details of the ammeter. I was asuming it was a analogue meter with either two terminals on the back that actualy measured the current passing between the two terminal OR it used a current transformer with the winding connected to the meter. To use the type with a current transformer you just thread ONE (NOT BOTH.) of the live wires through the hole in the current transformer. The black ring in the middle od you hand is a current transformer.
What is the green and white thing with two screw connections in the same picture ?
Les.

Click to expand...

It looks like a cheap Chinese LED meter, and a quick search on Aliexpress found this:


So he needs to connect (a feed from) both the red and the black wires to the two terminals on the meter (doesn't matter which is which), and feed either the red or the black wire through the ferrite ring.

This is from FB from a purchaser of the same unit.

"this volt and amp meter ,uses a current transformer to detect amp usage plus it needs a direct connection to the AC supply you are measuring. test to see it came one seems ok will connect it up permanently later to monitor total usage in my workshop"

Appears it needs both the ferrite ring for current and direct connection for the voltage, and the readout supply ??
Must need to unload them, was $13.80, now $1.41 !!??

The pictures in post #1anf post#7 now makes sense. The thing that is maked LED is not just an LED it is the display part of the ammeter. It picks up it's power via the connections X1 & X2. They each connect to the two lives. (So it gets it's 220 volt supply that way. ) The single horizontal lin to the right of the LED marking is the twin wire going to the winding on the current transformer. The circle at the right hand end of that line is showing the current transformer with one of the live wires to the motor threaded through it. (It does not matter which one you thread through it.)
Edit. I think it would be a good idea to add a fuse in each of the wires going to X1 & X2. I suggest about a 1 amp fuse.

Les,

Thank you very much!