Seems like it would be fine to me.
Rotary Phase Converter
- Thread starter Ralphxj
- Start date
Seems like it would be fine to me.
I'm in process of building my own 7.5 HP RPC.
What relay did you use? The plan that I intended to follow called for a Steveco 90-66. That has been discontinued.
This is the one I purchased: https://www.zoro.com/value-brand-potential-relay-35a-pick-up-166-to-180-5mly9/i/G3262007/
I think the PM talks about having to modify the Steveco?
Yes and that is holding me up. I don't know enough to know what it can be substituted with that will work without modifications. The subs that I have found look like sealed units, so IDK if they can be modified. Doubt it.
Why do you need to modify the Steveco? Isn’t it just a potential relay?
Potential relays are not really designed for switching the amount of current that is put out by start capacitors in RPC. Usually a potential relay controls(usually a 30 amp air conditioning) contactor or Motor starter. This also can be achieved by using a delay timer relay that controls the start capacitor contactor.
Also you can run your three wire control Circuit in parallel with a momentary start contactor for the start capacitors. In this situation you just have to hold the start button until the RPC is up to speed then like go. Just like starting a dryer 30 years ago.
Still planning details of my converter build, I would like to add some sort of display or gauges that will display the load on the system and how much power is available for use. Something similar to this type of gauge for each of the 3 lines:https://m.ebay.com/itm/Digital-LED-...0V-100A-110V-240V-Amp-Volt-Meter/222578792663
That will tell me how many amps I'm using at any given time, but how/where do I measure the amount of power available? Everything I see online is listed by HP ratings, how do I measure the power my converter is putting out on a given setup? On a standard house power feed, I know the limits of what's available based on the size of breaker my line is using, but how do I know on a rotary converter? Just want to know when/if I'm getting close to pulling too much power and I like things that light up!
That will tell me how many amps I'm using at any given time, but how/where do I measure the amount of power available? Everything I see online is listed by HP ratings, how do I measure the power my converter is putting out on a given setup? On a standard house power feed, I know the limits of what's available based on the size of breaker my line is using, but how do I know on a rotary converter? Just want to know when/if I'm getting close to pulling too much power and I like things that light up!
I am using exactly what you link to, but a little different. On my 5 hp RPC I have tested the **** out of it. I have one of those metres on the single phase side and three of those metres on the three-phase side. They’re all installed in 6 x 6 x 4“ box. I know what my single phase restriction is, 40amps on that line. After my RPC I go into a three phase fused disconnect that I have 15a fusing in. The fusing is mainly to protect the 6 kVA 600 V transformer after it. I’ve fixed/repaired and built A few in my day.Still planning details of my converter build, I would like to add some sort of display or gauges that will display the load on the system and how much power is available for use. Something similar to this type of gauge for each of the 3 lines:https://m.ebay.com/itm/Digital-LED-...0V-100A-110V-240V-Amp-Volt-Meter/222578792663
That will tell me how many amps I'm using at any given time, but how/where do I measure the amount of power available? Everything I see online is listed by HP ratings, how do I measure the power my converter is putting out on a given setup? On a standard house power feed, I know the limits of what's available based on the size of breaker my line is using, but how do I know on a rotary converter? Just want to know when/if I'm getting close to pulling too much power and I like things that light up!
This was my last 20 hp build.
Now it’s very difficult to accurately measure amp draw from an RPC as there is something called reactive amps. This creates a very fudged number using a clamp on or hallway current counter, as both are recorded. A heat load Will straighten out these feed numbers. I’ll get into that with another video if you wish.
I wish more people knew about VAR & RMS & Watts. And how to properly measure them and make them all work together. Maybe a sparky engineer can chime in, that has RPC experience.
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How do you know the limit is 40a? Is that the breaker size of the feed line, or the actual amount of power the RPC is able to handle? If it's the actual RPC limit, how did you get that number? That's the part that confusing me.
I took a bit different path on the start circuit, not using a potential relay. I used a ALLEN-BRADLEY 800T-J5A, https://buy.eescodist.com/Selector-...White-Insert-30-5-mm/800T-J5A/p/78118063879-1
This is a 3 position switch where the third position is a momentary position. Starting is like starting a car, first position is off, turn to second and power up and third is start and release. I have a power relay, second position, and a start relay, third position, that connects in the start cap for the few seconds it takes to spin up. It has worked for many years in this configuration.
When I built this RPC I followed the Hanranhan document. I have refered people to it many times but now find t hat it is not on the web where it used to be. Does anyone have a url for it or maybe a copy they could send me?
Thanks
lg
no neat sig line
This is a 3 position switch where the third position is a momentary position. Starting is like starting a car, first position is off, turn to second and power up and third is start and release. I have a power relay, second position, and a start relay, third position, that connects in the start cap for the few seconds it takes to spin up. It has worked for many years in this configuration.
When I built this RPC I followed the Hanranhan document. I have refered people to it many times but now find t hat it is not on the web where it used to be. Does anyone have a url for it or maybe a copy they could send me?
Thanks
lg
no neat sig line
The website is gone, but not forgotten! https://web.archive.org/web/20010211164437/http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
My single phase feed-line/Circuit is not allowed to burn down my house/shop and everything has to be sized correctly. This is part of most electrical codes.
There is also generator codes. I’m not sure if they’re applicable to your situation. This can be found under the NEC article 455–6
Everything has to be properly sized prior to. Everything has to be properly sized there after. Branch circuits are only allowed (in most jurisdictions to maximum of 20 A). Voltage regulation is a little bit taboo above 300 V in residential. In some situations you’re allowed and in some situations you are not.
Most code situations state, no more than 150 V to ground (is permitted in North America, for residential zoned property) Per hot line, distributed.... is allowable.
And I’m OK with being challenged on this (with proof) to prove me otherwise.
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I'm not sure I follow any of that?? I understand if you have your feed line on a 40amp breaker you can't pull more then 40amps, but my question is, how do you know if your RPC will be able keep up? I know if my RPC is 30hp it will keep up with a 3hp machine. But what if I have a 5hp RPC and try to run a 5hp machine? Or say a 10hp RPC and I try to run 2 3hp machines at once. How do I know the limits of my RPC and when I'm getting close to it's limits?
The rule of thumb is the RPC should be two times bigger than the machine/s motors that will be ran at any one time . This is to provide the third (generated) leg with enough power to start a machine/s. The other rule of thumb is the amperage required at any one time should be 1.73(+++) times greater at single phase.
You will know your limits when you start popping the single phase breaker during long or hard starts.
Sizing correctly from the beginning sometimes is a challenge when building your shop.
Maybe you should contact North American rotary phase converter’s or American rotary phase converters. They both have good websites and lots of information and are pretty reputable. You can also go with Phase perfect.
Thanks, I will update my bookmark.
So the switch I referred to above is the start switch in this schematic. The run position pulls in 1R and the start position pulls in 2R momentarily while the rpc spins up. I find it works great for me.
lg
no neat sig line
firebirdparts
Well-known member
It was a long time ago, and I was building from a plan that a lot of guys used on practicalmachinist. Probably I used the same relay. Got it from Grainger.
Grainger still sells a potential relay for single phase start caps for about $17. That might do the job, but I am not enough of an electrical engineer to say. Manual startup would certainly work too. Even a timer would work.
matt_i
Well-known member
Either will work, my thoughts are that the timer can work, I have used one, but its an "open loop" device. If it gets colder than normal and the idler does not start as fast, the time delay which was originally selected might not be sufficient.
The potential relay is a closed-loop device, will work no matter the temperature. To that end, if the idler gets loaded down to the point where the monitored leg loses enough voltage (could be a heavy load in the "field" being started), the potential relay will pull back in automatically in an effort to react.
When shopping for a good motor, other then checking that it spins smooth and the bearings are good, how else do I know I found a suitable motor? I'm looking at HGRinc.com and might run up there to shop. How do I know if a $40 motor will work as well as a $120 motor or a $180 one?
Radix2
Well-known member
There really is not much to wear on a 3ph motor besides the bearings - about the only other thing you can do is to check that the windings have the same resistances and than they are not shorted to the frame. On an open frame motor you could look inside for signs of overheat and to see if it is filled with dirt and crud..
I agree totally and but I would suggest to stay away from 0PD if it is filled with Crud or it will eventually be filled with Crud. This is all dependent on it’s prior workplace and work place that you’re going to subjected to.
the 4 & 6 pole have their advantages with noise and start times.
the TEFC have their advantages that contaminants aren’t in there
The TEFC with fin cooling also have their advantages for maintaining cooling.
But with each step expect to pay more.
opd? Tefc?