installing a mag starter

[low51fan]

Hello
My first post here please excuse my jumping right into asking for help. I have been setting up my garage for a while and have run 50 amp service for my welder and 30 amp for my air compressor. I have just bought the magnetic starter to finish up my a/c install but am looking for some help as to how to hook it up.

I had originally run a 30 amp line to my pressure switch and ran my 5 h.p. through the pressure switch also. After reading on this site I have concluded I need to install the mag starter it had one originally but I was told by a "buddy" I did not need it. I have 220 service up to the unit along with a functionilne pressure switch so I assume the install is pretty straight forward. I have attached 2 photos.

Thabks in advance
Jim S

 

[bsaint]

Your pressure switch would have to be rated for more than the breaker you're feeding the compressor with. Which for 5 hp single phase is a lot more than your standard pressure switch.

By the time your compressor pulls thirty amps to trip the breaker it may cause a lot of damage. The good thing about a mag starter it has overloads.

 

[low51fan]

ok bsaint I would agree thats why I am installing the mag starter? I guess I am looking for some help as how to correctly wire the starter. I was following a post a while back and the guy had a similar situation as mine but it was determined it was improperly installed and basically did nothing to protect the motor. I cannot seem to locate that particular post so I thought I would ask.

 

[bsaint]

Well first off I'm not a electrician by trade, I am more automation and controls.

You want to use the pressure switch as a control. Your mag starter is basically a high power relay, triple pole single throw. I don't want to tell you how to wire the power from your building (it's not my thing) but here is how I would wire the control end. Make sure your pressure switch has a lever on it, it will eliminate a second switch. Tap off one incoming leg to one of the two incoming terminals on your pressure switch (I believe it's marked L1) Then come off the T1 (the terminal that's "switched") to one side of the mag starter coil. I don't remember Nema but for IEC it's A1. Then go from A2 (the other terminal on the coil) to either the other incoming leg or neutral depending on the mag starters control coil voltage rating. It's a very basic control circuit I'm sure you can do.

 

[Norcal]

That motor is 20 amp nameplate so your breaker should be 50 amps and your overloads set to 30 amps.

This very incorrect, the O/L relay is set to the motor amperes, not above or below.

 

[readymix]

I have the schematic you need printed and hanging on my garage wall. I'll try to get a photo of it in the morning when I head out to work. If not then, I'll get it tomorrow evening.
I could also take pics of how my starter is wired. I just installed it last week.

 

[bsaint]

This very incorrect, the O/L relay is set to the motor amperes, not above or below.

Like I said Im not an electrician.

And we have plenty of special applications where the heaters are set below the nameplate amps.

 

[bsaint]

I was trying to think where I got that 1.5x and I realize its not 1.5x.

I was told you can set overloads to nameplate amps or based on service factor

 

[low51fan]

I appreciate the responses so far. Readymix I would appreciate the pics if you could find the time. I have the breaker box covered I have a 50 amp breaker and have run 6 gauge wire to the air compressor unit. I have run the unit for a few cycles and it works fine without the starter but am told I am putting too much stress on the motor.

Thanks again

 

[readymix]

No problem. I'll get the photos tonight.

 

[Gary S]

Check the manufacturer specs for the compressor and check to see if there are any specs on the pressure switch. Most 5hp compressors don't need a mag starter. The pressure switches are often rated at 25-30amps so they can handle motors of this size. The pressure switch is just a contactor. A mag starter is just a heavy duty contactor.

My 5hp compressor manual plainly states that a starter is not needed. The pressure switch is rated high enough to handle the motor load.

 

[low51fan]

Gary

I was told the motor had to have an overload protector in order not to need the starter. If the motor had the overload protector should it not have a reset button on it?

 

[readymix]

Here are some pics. Let me know if you need more or a different angle.

 

[readymix]

More

 

[readymix]

They are not showing up on my phone. Can you see them?

 

[readymix]

Now i can see them

 

[1/2 Cup]

This very incorrect, the O/L relay is set to the motor amperes, not above or below.

Correct on that one.

 

[C96]

Gary

I was told the motor had to have an overload protector in order not to need the starter. If the motor had the overload protector should it not have a reset button on it?

Jim, you are correct on this. Just because the pressure switch has a high enough rating does not mean you can forget the starter. You still need the overload protection the mag starter provides. Use the wire diagram that readymix provided. Most adjustable overloads already have the 125% max overload factored in, so just set the dial to the motors FLA.

 

[low51fan]

readymix I really appreciate your pics but I think with my lack of knowledge in the electrical field I may be better off if someone could help me with my particular set up.

I am going to post everything I have and hope for some input.

 

[readymix]

I can help if you let me know exactly what you have.

 

[low51fan]

Here are the pics

The compressor was running fine but after reading some information on this site I thought it best to install the eaton starter.

A few details, I have run 8 ga. wire on a double 30 amp 230v system. I had the compressor running through a pressure switch set to shut off at 175 psi. It ran great before but again I am looking to install the mag starter.

I think the starter should be wired as follows:
run my wire from th breaker to L1 and L2, run the motor to T1 and T3? The starter came with the black jumper wire from L3 to T2 guess I am unsure of why. My first question is am I correct in my thoughts on the wiring?
I have tried to hook up my pressure switch a few different ways one included blowing the whole main breaker.

I am not an electrician by ANY means but did wire my main panel for both the 30 amp air compressor and a 50 amp for my welder it was inspected and I did this correctly. I have spoke to a few residential electricians but am uncomfortable with the answeres I was given (especially since one was what blew my whole main breaker.

Thanks in advance

 

[readymix]

Looks like you have it correct so far. Just need to wire the input power to L1 and L2 on the starter (top), and the motor to L1 and L3 on the OL (bottom) then add the pressure switch.

Look at the attachment for where it says "remote pilot device"...that would be the pressure switch.

 

[alfredeneuman]

Be sure to hook it up as "Common Control w/o Auxiliary Contact" as the label directs.
The aux. contacts are also known as holding contacts, and the motor won't turn off when the pressure switch is turned off.

 

[low51fan]

Thanks readymix and alfredeneuman I really appreciate your input I was really getting frustrated. I think I have a handle of the main power wires and where to put the wires to the motor. With the information you guys gave me I will go back over the pressure switch diagram

 

[low51fan]

Now that I am running the starter I have my line running in connected to the L1 and L2 on the starter and one wire for the pressure switch running from L1 on the starter. Should this wire connect to the terminal marked line or motor on the pressure switch or does it matter?

 

[readymix]

doesnt matter.

 

[low51fan]

ok didn't think so. I will run it off the motor side just because I'm runing my motor off the L1 and L2.

Can I get some input on where the other wire would go from the line side of the pressure switch to where on the starter? If I am reading the diagram right is says the left hand side of the coil terminal?

 

[readymix]

Can you take a pic of the top of your starter? The terminals look different than mine.

 

[low51fan]

Here are the pics two of them are the top of the starter the one shows the red wire connected behind the black line coming in on L1 you can see it has one more spot for a spade connector behind it. There are two more small ga. red wires one attaches behind the other main line (red wire) connected to L2The other small red wire attaches to a spade connector behind L3 (the jumper wire) they both run down to the bottom half of the mag starter and attach to #95 and #96 respectively.

I think its all set but I just cannot figure out where the last wire goes from the pressure switch?

thanks again

 

[readymix]

You said "the one shows the red wire connected behind the black line coming in on L1 you can see it has one more spot for a spade connector behind it."

That spade is terminal 1
The two connections in front of that are L1

Moving to the right,
the one on the rear is terminal 3
The two connections in front of that are L2

Moving to the right,
the one on the rear is terminal 5
The two connections in front of that are L3

Does that help explain where the connections are? I know it is confusing

 

[low51fan]

uhhggg nope I went backwards.

How can something so simple looking be that difficult.

If I read the install instructions under COMMON CONTROL (WITHOUT AUXILIARY CONTACT)

it says

1. connect the no. 13 terminal of the remote pilot device to the left hand side of the coil terminal.

2. connect the no.1 terminal of the remote pilot device to the L! terminal.

For the number 2. part of that statement I understaood it to say take the red wire from the pressure switch terminal line marked "LINE" and run that wire to the L1 spade connector attached to where the black line comes into.

Now after rereading it it says connect the NO.1 TERMINAL OF THE REMOTE PILOT DEVICE TO THE L1 TERMINAL. Is the remote pilot device not the pressure switch?

After reading your response I see to take the No.1 terminal and run a short jump wire from that to the L1 terminal? I see basically no mention of what to do with the pressure switch wire at all the way I read it now?

 

[readymix]

I'll pm you my number

 

[low51fan]

I really appreciate all your help on this readymix. It is up and running time to start cutting and welding on the Mercury.

 

[MTW]

Hello
My first post here please excuse my jumping right into asking for help. I have been setting up my garage for a while and have run 50 amp service for my welder and 30 amp for my air compressor. I have just bought the magnetic starter to finish up my a/c install but am looking for some help as to how to hook it up.

I had originally run a 30 amp line to my pressure switch and ran my 5 h.p. through the pressure switch also. After reading on this site I have concluded I need to install the mag starter it had one originally but I was told by a "buddy" I did not need it. I have 220 service up to the unit along with a functionilne pressure switch so I assume the install is pretty straight forward. I have attached 2 photos.

Thabks in advance
Jim S

Jim, here is a quick sketch of a wiring diagram for you and others.



You have a IEC 3 phase starter and a 1 phase motor. IEC starters are balance sensitive on the overload relay portion. When you run the motor current through 2 poles only, you will have balance problems. The overload relay will nuisance trip on you because of the unbalance from zero current in the third overload heater. To correct this wire like the sketch shows, that is connect the power to L1 & L2, then connect the motor to T1 & T3. Then install a jumper from L2 to T3. This will route the L2 current to L3 pole and create a balanced condition in the overload relay section.

For the controls portion tap L1 for power and run to the pressure switch line terminal. From the motor terminal on the pressure switch run it back to the starter coil left terminal (located on the top of your starter).

Tap L2 for power and run to the overload relay NC (normally closed) terminal 95. From the overload relay NC (normally closed) terminal 96 run it back up to the coil right side terminal.

Thus wired the pressure switch will control the left side of the coil power and the overload relay will control the right side of the coil power. Both will need to be on (closed) to get the starter energized. If either one opens the starter will be turned off.

A few other suggestions.

It is a code requirement to have a disconnect at the motor starter location as shown, unless your supply breaker is within sight of the starter location and less than 25' away. A lever switch on the pressure switch is not adequate for the code when using the magnetic starter.

Mounting of the starter on the compressor is a high vibration location, and this can cause problems over time. Either mount the starter on the wall, or brace the enclosure top and bottom to reduce vibration on the sheet metal enclosure. The starter and it's enclosure will thank you if you mount it securely to minimize resonant vibrations. Otherwise it may crack the enclosure or cause the connections to loosen over time, causing problems for the starter and compressor.

For the overload setting, set it at the nameplate amps of the motor. If it trips at that setting, you can turn it up to the maximum value of the SFA (service factor amps) and no more, to provide proper overload protection for your motor. Keep the setting as low as possible for the best protection of the motor.

Using a magnetic starter will greatly extend the life of your pressure switch contacts, and give long reliable service when done correctly.

MTW

 

[Caldreamz]

@low51fan and @MTW,
I have the same setup that I am trying to put together. Same Eaton mag switch running a 5hp compressor (in my case a Quincy QT-54). The Eaton box has the same connectors, although the red wires are run out to the side and easier to see. It seems you guys had a separate conversation that didn't end up in this thread. The diagram MTW posted seems to have a jumper from T2 to L3 but the text says install a jumper between L2 and T3??? I understand the pressure switch only needs a wire to line in and another to motor out (same side poles) to complete the connection and trip the mag switch. Can you post some pics of your final setup?

My Eaton came from the factory with:
A black jumper from lower T2 to upper L3
A red jumper from 95 to a spade lug behind upper L3
A red jumper from 96 to upper L2

 

[Norcal]

This is a thread from 2013.

 

[Caldreamz]

yup, thank goodness nothing gets deleted.

 

[Caldreamz]

Closing out my addition to this thread. I was able to get it sorted in another posting about the initial wiring of the Baldor motor.

To confirm:

1) Leave all the factory jumpers alone (lower T2 to upper L3, 95 to coil behind L3, 96 to upper L2)
2) Connect motor to T1 and T3
3) Connect line to L1 and L2
4) Connect pressure switch line 1 to mag switch L1
5) Connect pressure switch load 1 to mag switch coil behind L1

I think #4 and #5 could be reversed (line 1 and load 1). The idea is to let the pressure switch make the connection and it doesn't matter which way the electrons flow.

Thank you again to @Bert_

 

[wyliesdiesels]

Closing out my addition to this thread. I was able to get it sorted in another posting about the initial wiring of the Baldor motor.

To confirm:

1) Leave all the factory jumpers alone (lower T2 to upper L3, 95 to coil behind L3, 96 to upper L2)
2) Connect motor to T1 and T3
3) Connect line to L1 and L2
4) Connect pressure switch line 1 to mag switch L1
5) Connect pressure switch load 1 to mag switch coil behind L1

I think #4 and #5 could be reversed (line 1 and load 1). The idea is to let the pressure switch make the connection and it doesn't matter which way the electrons flow.

Thank you again to @Bert_

sounds correct.

the reason for the jumper from T2 to L3 is because of the 3Ø solid state overload you have. It has phase loss protection, so if current isnt running through all 3 overload CTs, it will instantly trip

 

[meandmyshop]

Closing out my addition to this thread. I was able to get it sorted in another posting about the initial wiring of the Baldor motor.

To confirm:

1) Leave all the factory jumpers alone (lower T2 to upper L3, 95 to coil behind L3, 96 to upper L2)
2) Connect motor to T1 and T3
3) Connect line to L1 and L2
4) Connect pressure switch line 1 to mag switch L1
5) Connect pressure switch load 1 to mag switch coil behind L1

I think #4 and #5 could be reversed (line 1 and load 1). The idea is to let the pressure switch make the connection and it doesn't matter which way the electrons flow.

Thank you again to @Bert_

Thank you both @Bert_ & @Caldreamz

This helped me a ton in getting my new eaton mag starter wired up. Same model, and same situation. Compressor didn't come with a mag starter, and instead was wired directly to the pressure switch. It would start with new capacitors, but would still struggle a bit. Starts up immediately and reliably now with the mag starter. Also upgraded the old centripetal unloader valve system to a modern pressure switch unloader valve in the same go with the mag starter. Has made me happy to use it now.