3 phase starter circuit

[madmachinst]

So here is the latest and greatest.


Has a 240VAC 16 AMP electromagnetic switch sending power for pony motor and to switch timer relays. Power dies then RPC only starts when I press the green button again. Will use a 120 Amp contactor to send power from idler to 3 ph panel. Probably will have to use aux block on 200 amp contactor to activate another timer relay so that the output contactor (120 amp dealie) will close and send power to 3ph panel. Man I am running out of cabinet space.

 

[J_R_Thiele]

Some suggestions.
Have magnetic switch provide power to timer #1 and #2 when powered on. Timer #1 controls pony motor contactor with power for pony motor comes from L1 and L2 ( not through Magnetic switch). When timer #1 cuts power to pony motor contactor it starts power to two pole contactor, thus powering idler. After idler is started and running for 1 or 2 seconds, timer #2 powers 3 pole contactor connecting idler to terminal block connecting to 3 phase panel. This terminal block also has run capacitors attached, thus run capacitors only function after idler started.

By not having Magnetic switch providing power to pony motor, pony motor could be larger than 2 HP if needed.

 

[madmachinst]

By not having Magnetic switch providing power to pony motor, pony motor could be larger than 2 HP if needed.

Thought about that and it really complicates teh wiring but will try. am hoping that 2hp is more than adequate. In a different prev post some one told me ( Jim Rosen post #5) ( also look at post #23 different poster same numbers)

50 HP rotary, "To pony or not to Pony ?" That........

that a 1.25 hp motor ought to do the job. JR your PM is full.

 

[J_R_Thiele]

My PM box now has some room.

If it makes it too complicated, stay with what you have planned.

What size box do you have to work with? It may be worth doing a search on craigslist for NEMA. I find a 20 x 20 x 7 for $160., but also a 48 x 36 x 9 for $50. If there is a nearby Habitat for Humanity store it may be worth looking there also.

 

[madmachinst]

Here is the box I have
Yeaborn Cold Rolled Steel 16"x12"x8" Indoor Outdoor Electrical Enclosure Box | eBay
for all 3 contactors and relays to be mounted outdoors. The NEMA 1 box in my bloopers will have the main breaker and magnetic switch. Would love to have my balance caps in there too, or should I put them in the outdoor sealed box? BTW, you think that a SUPCO TD69 would be all I need for the output contactor to delay its closing of the contacts? Or am I better off going with another Idec RTE-P1AF20 relay?

 

[J_R_Thiele]

I have no reason to think the SUPCO TD69 would not work.

That is not much room. The control wires should be routed separately from L1 and L2. Any way to put the timers inside and the contactors outside?

The balance caps need to connect to L1, L2, and the generated leg L3. As far as I know it does not matter where they physically are. You could wire them with each machine, if those boxes have room. Just looked and the 2014 NEC says that if that is done they need to be on the line side of the motor overload relay.

 

[J_R_Thiele]

Fitting what you have into that size box will be challenge.

Here are some pictures of my capacitor start RPC with a 10 HP idler. I was going to fit a simpler version in a much smaller box, but decided a larger one was worth the cost and wall space.

This also allowed me to use a NEMA 4 motor controller that I found at a very good price while looking for a smaller one. If I ever to increase the idler size I am all set, though plan A is to add an additional idler.

The first two pictures are of the box and components. In side the door I have a schematic (PX 3) and an outline of how the components are laid out in the box (PX 4). Sorry for the pictures not being upright.

 

[madmachinst]

I'm thinking really hard and just not seeing it. That output contactor does not isolate the idler from the caps so when you trying to start that idler will have the same problems you discussed of caps causing what you said in post #10 so why have the output contactor? I mean after all, If I plan on using 3 phase that day then will flip the 2 pole breaker and then hit the magnetic switch. Then by the time I ge to a machine to flip that main power breaker on the cabinet will take a while. I just don't see the need for that output contactor. all the cabinets for start cap rotaphases don't have that. Now OTOH I am open to utilizing an ICM450S to open or close a contactor if I have an intermittent phase problem. I don't think shutting things down when things go bad is a better solution than fixing the problem. I just don't see the feasibility. So please explain what the 2nd contactor does? Your starting that phase converter 1st thing so really no overload.

 

[J_R_Thiele]

You are correct, it is not an issue with capacitor start RPC's. The issue with them is getting the start caps disconnected. If the contactor doing this is too small for the load, the contacts weld shut and the start capacitors blow.

The 3 pole output contactor WILL isolate the caps from the idler IF you wire the caps between the 3 pole contactor and the breaker box the machines are wired to. I should have made where the caps need to attach clearer. Another option is to have a 3 pole breaker to connect the run caps to L1 L2 and L3. As mentioned before, you also could have the run caps wired in at the machine, so they connect when the machine is lowered up.

 

[J_R_Thiele]

This drawing may help.

Magnetic starter starts timer #1, which starts and then stops pony motor.

As pony motor power stops, timer #1 closes 200 amp contactor, connecting L1 and L2 to spinning idler.

Power supplied to 200 amp contactor also powers and starts timer #2. After short delay timer 2 closes 3 pole contactor, which allows power to go breaker box and powers run capacitors. An alternative to the 3 pole contactor connecting L1, L2 and L3 to the breaker box and run capacitors would be a 2 pole contactor connecting the run capacitors to L1 and L2.

 

[madmachinst]

your drawing looks like what I had in mind except I'd use that same signal that triggers timer 1 to trigger relay 2 also ( just longer delay). Now your said 2014 NEC said caps on line side of overload relay and from what I understand your drawing is showing it on load side ( load being the 3 phase panel). Problem is that both the Larson drawing and your setup aren't like that last drawing you made. I am just hoping that by suddenly applying full surge of power to those caps nothing weird will happen, like wires getting really hot or something.

 

[J_R_Thiele]

Using the same signal for both timers is fine. I drew it out that way at first, but the drawing was more confusing, so I redrew it with pony motor related on the right, and the rest on the left.

My reference to the 2014 NEC is for when the caps "are not an integral part of the rotary-phase conversion system, but are installed for a motor load..." This applies if the caps are located at the machine, not when they are mounted in the RPC system enclosure.

My system is a capacitor start system, not a pony motor start, so yes, it is different.

In the Larson drawings contactor 1 controls power to the pony motor. Contactors 2,3, and 4 control power to the idler, and also connects the capacitors to the idler. Those capacitors go between L2 and L3. Contactors 5 and 6 connect L1,2 and 3 to the load terminals of the RPC. The second page shows two timers, with relay 1 controlling the pony motor through contactor 1, the idler through contactors 2,3 and 4. Relay 1 also powers relay 2, which controls contactors 5 and 6. Both timers are time delay relays, but we do not know what times they are set for.

NEC 2014 455.21 states that power to equipment shall not be supplied until the RPC has been started. Timer 2 and contactors 5 and 6 provide a delay, so power "out" is not supplied until idler is spun up and powered. This insures that single phase power cannot go to equipment if someone happens to start a machine at the same time the converter is being started. My system does not have this provision. Like your situation, there is a time delay while I go to a machine so I am comfortable with this.

The capacitors are fine with the full power, assuming they are of the proper voltage, and the wires are sized for the current they carry.

The most practical way to simplify your system is to ditch the 200 amp two pole contactor and replace it with a 3 pole contactor. You can then wire in the caps between the circuit breaker and the 3 pole contactor. In doing this you only need the one timer you are already using. See the drawing below.

I just went back and looked at an earlier post of yours in which you mention having a 3 pole contactor, and you may have been suggesting what I drew out above. My apologies for not picking up on that.

 

[madmachinst]

That is incredibly smart. Yes that contactor I have in the picto-drawing is photoshopped to only show 2 poles. I'll leave it 3 poles. My question is this, would things be 'fool proof safe' if I was to go with the plan in post 30 rather than the plan in post 32? I mean when that idler starts right up, those caps will start getting juice. Is there no advantage to isolating caps till a few secs after idler is running on its own power? Would seem safer in my opine. If not then my shopping list is fulfilled and I start putting this rube goldberg all together. Paragraph 2 in your last post clarifies a lot for me. You have been an absolute tremendous help.

 

[J_R_Thiele]

I hope someone else will look at the drawings in posts 30 and 32 and provide their thoughts. Sometimes a fresh set of eyes will notice things being overlooked.

The plan in post 32 has one less timer, and one less contactor. Given your limited room, that is a significant advantage.
Neither plan has an overcurrent device between the converter and the breaker box.

Of more concern, neither plan has a means to shut down the system, or not provide just single phase current in the event of a phase loss or failure of the idler to start. Most probably this would be from a thrown or broken belt between the pony and the idler. With those mounted outside you would have no easy way to know this. Will need to think on that one a bit. My initial thought is to make it a semi manual system where you monitor a pilot light or volt meter, confirm that it is started and respond by releasing a switch, or pressing one. This must have been addressed before...

 

[madmachinst]

I hope someone else will look at the drawings in posts 30 and 32 and provide their thoughts. Sometimes a fresh set of eyes will notice things being overlooked.

Same thought here, but so far you seem to be the biggest help of all. Of course I have a guy in Midland TX who repairs oil rigs and knows a bunch about VFDs, motors, and such. I also have a guy that knows a ton about capacitors and motors cause he repairs them all day. so I will drop by those folks.

The plan in post 32 has one less timer, and one less contactor. Given your limited room, that is a significant advantage.
Neither plan has an overcurrent device between the converter and the breaker box.

I am not the least bit concerned with overcurrent ( maybe cause I really don't know what I am doing?). Just in case, you have any links to what you are talking about and prices? So I can get a better idea. I just have to ask you the same question, do you think the 1st drawing you made is safer and more reliable than the second one?

Of more concern, neither plan has a means to shut down the system, or not provide just single phase current in the event of a phase loss or failure of the idler to start. Most probably this would be from a thrown or broken belt between the pony and the idler.

OMG don't tell me instead of a timer I should have gone with a SUPCO potential relay off the idler, that was my original idea from a long time ago.

With those mounted outside you would have no easy way to know this. Will need to think on that one a bit. My initial thought is to make it a semi manual system where you monitor a pilot light or volt meter, confirm that it is started and respond by releasing a switch, or pressing one. This must have been addressed before...

Didn't want to use this, but may just have to get an ICM 3 phase monitor. will mount that indoors and line up the relay on that with the 200 amp contactor. Wish the relay on those was Double pole, but I think single pole should work. Maybe the ICM will shut it all down in the event the idler isn't outputting over so many seconds and that will stop the system from single phasing for too long? No need for supco potential relay?

 

[J_R_Thiele]

The overcurrent device I am referring to would be a 3 phase molded case circuit breaker, which protects the line between the RPC and the panel or machine. Suppose you had your 50 HP RPC powering two 20 hp machines with each machine wired directly to the RPC. If there is a short in one of the lines with the present design, the circuit breaker sized for the RPC needs to open. It would be better for each 20 HP machine to have its own breaker located in the RPC and sized to protect the system between that point and the machines own motor overcurrent devices.

The SUPCO relay is usually used to remove start caps from the system. It could be used to shut down the RPC if the idler is not spinning- but this involves a redesign of the control system.

The simple solution is to wire in a voltage display of L1-2, L1-3 and L2-3 by your start/stop switch. After hitting "start" watch the meters. When the contactor closes you will see voltage between L1-2. You then should see voltage between L2-3 and L1-3, L3 being the generated leg. If you do NOT see voltage in the generated leg, hit the stop button. This requires that you stay by the start/stop for a short time. It also allows/requires you to look at the voltage balance each time the RPC is started. Here is an inexpensive meter uxcell AC 0-300V Analog Panel Voltage Gauge Volt Meter 85C1 2.5% Error Margin - - Amazon.com. This is not an endorsement of that product- it was the first inexpensive analog voltmeter I saw. You could also use digital volt/ammeters, but will need to be more attentive to the actual numbers displayed.

You are asking which of the designs is safer and more reliable. What I know about electrical matters comes from my reading and studying. I have NO formal training. I have read parts of the 2014 NEC as I was getting a building permit to install my homebuilt RPC. I designed my RPC based on the 2014 NEC. The county required I have engineer approved drawings. They informally suggested an engineer to talk with. He was kind enough to not charge me to review my plans, then have his firm convert my plans to their drawings. He did not suggest any changes to my plans.

In my opinion: Safe and being built to NEC standards are not the same. Both designs are safe without the 3P circuit breaker IF run to a breaker box. Simpler is usually more reliable, so my preference is for the design in post 32- but with the 3 voltmeters added as mentioned above. This is not the same as phase loss protection.

We need input from someone with who knows more than I do regarding phase loss protection. My concern is this- with an RPC the voltage in the generated leg drops with an increase in load. This can occur with the inrush current of starting a motor. It would not be good if the system shut down when a second motor was started.

 

[madmachinst]

The overcurrent device I am referring to would be a 3 phase molded case circuit breaker, which protects the line between the RPC and the panel or machine. Suppose you had your 50 HP RPC powering two 20 hp machines with each machine wired directly to the RPC. If there is a short in one of the lines with the present design, the circuit breaker sized for the RPC needs to open. It would be better for each 20 HP machine to have its own breaker located in the RPC and sized to protect the system between that point and the machines own motor overcurrent devices.

have a 3 phase mainbreaker panel after this rotaphase. Every 3 phase item is getting its own breaker. That is not enough. BTW SquareD QO breakers. So far only 1 3 hp ( maybe in future will be 5hp) CNC mill with VFD, one manual mill 3hp and one 20 hp CNC lathe.

The simple solution is to wire in a voltage display of L1-2, L1-3 and L2-3 by your start/stop switch. After hitting "start" watch the meters. When the contactor closes you will see voltage between L1-2. You then should see voltage between L2-3 and L1-3, L3 being the generated leg. If you do NOT see voltage in the generated leg, hit the stop button. This requires that you stay by the start/stop for a short time. It also allows/requires you to look at the voltage balance each time the RPC is started. Here is an inexpensive meter uxcell AC 0-300V Analog Panel Voltage Gauge Volt Meter 85C1 2.5% Error Margin - - Amazon.com. This is not an endorsement of that product- it was the first inexpensive analog voltmeter I saw. You could also use digital volt/ammeters, but will need to be more attentive to the actual numbers displayed.
In my opinion: Safe and being built to NEC standards are not the same. Both designs are safe without the 3P circuit breaker IF run to a breaker box. Simpler is usually more reliable, so my preference is for the design in post 32- but with the 3 voltmeters added as mentioned above. This is not the same as phase loss protection.

I'll definitely go wit the second one. I am going with the ICM450S. I need more than a cool meter to look at. Need something that does something, but meters will always be good to know what is going on if ICM450s doesn't display that.

 

[J_R_Thiele]

It is unclear to me how you going to use the ICM450s with the design in post 32. With only one contactor it looks like it will be wired to the single phase "supply" side and the Idler "generator" side. It seems to me that it will be seeing a phase loss all the time, and then not permit the contactor to close on starting.

I do not know if it has to be wired "around" the contactor it controls, or if it is monitoring both line and load side.

Can you draw out what you have in mind?

 

[J_R_Thiele]

Was looking at the ICM450 installation guide and noticed figure 1 and noted that connection to the load side is optional, and the unit is powered from the incoming side 3 phase voltage.

I assume that it is actually powered by two lines, not all 3. If that is true then it could be wired to the magnetic start switch for power, and to L3. The line between the timer and the contactor is routed through ICM450 terminals 1 and 2. When the start button is pushed, power goes to the timer and to the ICM450. The ICM450 is initially on a delay setting,ignores that there is no voltage on L3. and contacts between terminals 1 and 2 are closed. When the timer switches the pony motor off and the contactor on the current is carried through terminals 1 and 2. After the idler has been powered for a few seconds, the TCM450 "delay" ends and it starts monitoring the voltages. If there is no voltage on L3 ICM450 opens the contacts between terminals 1 and 2, and the contactor opens, cutting lower to the idler and RPC.

 

[madmachinst]

I'm thinking so say ICM450 is powered by all three output legs when they are generated. 3 phase power begins to get generated and it keeps the NC relay closed which allows voltage to continue to be applied to 120VAC coil in the 200 amp contactor. I'd keep that in the NEMA 1 box so that I can keep an eye on the voltage balance on output. Will the idler start generating L3 with just pony rotating? I think that will work just fine. What you think can go wrong?

Got any suggestions on a panel mounted CT ammeter with 200 amp rating to check input on L1 and 2 for this thing?
Was thinking of using 3 Chinese LED 100 amp models for the output.