I had a brief discussion with you in another section a while back about using multiple idlers. I had been meaning to pick your brain and others about it more. Dave Kamp has a lot of threads, and in a quick search I didn't see what I was looking for. If you don't mind posting a link or three I'd appreciate it.
LOL! Dave posted a "neat enough" schematic, but it was actually a bit of a joke on those trying to make a simple thing complicated.
You don't really need it, because...
...I was curious where are you connecting the supplementary idlers ? To the output connections toward load/ working machines ? Or tee-ing from the primary idler, with a switch or breaker ?
I've read where some have simply started another machine, but unloaded, for stability. But was unsure if that idle machine was actually working as a supplementary.
.. well.. that's the "joke" part as to not making a problem out of a solution!
As far as the electrons that are being pushed give a damn?
Those situations are
all the same thing!
The schematic showed an RPC's output.. with a supplementary idler (AKA motor).. connected to it.
With a contactor!
Full stop!
Same as if it WAS a "load motor"!
And when onlining the supplementaries, the lower amount of caps in control box is not a problem ?
Actually it is the best part of the SOLUTION!
Not a "problem"
at all!
What you do is put the "right amount" of run/balance capacitance on the IDLER side of each "activate me" contactor for THAT idler, as if it were to be the ONLY idler.. because NOW it CAN be.. and often WILL be!
NO run/balance caps, are left inside the "starter/controller" box at all.
Only the start cap(s) and either of: the manual momentary, ELSE timer, ELSE potential relay.
In my case, that's the start cap Jim Gorman (Phase-Craft) calculated for the original 4-pole 17XX RPM Brazilian-built Weg 10 HP bought brand new on promo with free shipping for somewhere around $387.... IIRC.
The run/balance caps he used get PHYSICALLY moved into a Zorro-sourced Weigmann ready-made NEMA rated steel enclosure on the 10 HP motor as an enhanced pecker-head.
I use DEEP! 6" (6 1/4" exterior) or 8" (8 1/4" exterior) boxes in various sizes because space to work stuff easily is cheaper than swearing and skinned knuckles. They have plenty of room for the caps AND the contactor AND protective device
for that particular idler. They are "good enough" grey-painted steel NEMA boxes and much less expensive than Hoffman.
I have all manner of drills, hole-saws, nibblers, and annular cutters, do not WANT to go "Rons bat-f**k" cutting steel discs, Tig-ing them into knockout holes, bondoing, grinding, sanding the ugliness out, priming and painting and Blue-Coral waxing...... to make a
used box cost five times as much as a brand new box "just because I know HOW!"
Good way to go hungry off running out of time to electrocute yerself a Young's of Grimsby fish & chips supper!
Just add the "NK" (No Knockout) suffix when you order the silly box from Zorro online, and for small money, it shows-up on the front porch 2 days later with NO holes at all!
You need one hole for sure, more if it makes sense. Put those where they DO make sense and DONE. The paint is good enough as-had. Paint it p**y-pink if you dare and care to.
Now.. until you "bus" the contactors together?
You actually
have "n" (four, in my case) fully-capable stand-alone idlers WITH the proper run/balance caps
for their HP.
Just missing a starter & control.
Which we will "share" at the input side off the loadcenter.
Big enough wire and breaker to run the whole tribe when ALL are online. Even if that is not meant to be a "regular event".
"Code" sez each idler motor should then have a fuse or breaker rated to protect that lesser amperage. There's space in the big Weigmann box for bolting-in a "unit mount" SQ-D QO breaker. Or a trio of cartridge fuses. There's another option if you are up for some sheet metal or wire cage work.
As I need to do anyway, given the output hits a transfer switch (10 HP Phase-Perfect the other option), then a 27 KVA shared Delta-Wye transformer so I can re-derive a usable Neutral, and only THEN a 32-slot Square-D 3-Phase load center.
32 slots don't go all that far when a 3-pole breaker eats three at a go and you want a bit of unused space to group stuff for ease of remembering what is what.
NB: The "motor starter" function to NOT auto-restart after a power outage is inherent in the shared starter/controller box and the contactor actuation power sourced off a shared 24 VAC control transformer. And I'm not fussed about "heaters" for $250 NOS Reliance Duty-Master idlers anyway.
The 24 VAC control voltage goes dark, it
stays dark, so the idlers are
all disconnected until a human restarts the rig, manually.
Sooo... "in use" I always kick the 10 HP up onto the "step" first.
The Phase-Craft starter/control was built for it.
It is my heaviest starting load.
It is the largest, hence most-capable of starting the OTHER idlers, to wit:
3 HP, 5/7.5 HP, 5/7.5 HP. And the 10 HP itself, of course.
As the run/balance caps are ON the
motor-side of the contactor at each idler, I can drop ANY of them offline, the initial 10 HP included, "start" cap no longer involved anyway, just the control transformer.
The combo of 4 idlers can be mapped to the start/stop control and just FOUR toggle switches, readable in "Octal" notation as if on an old Varian Data 520i, General Automation SPC 12, etc.
Same number of "states" "OFF" or zero included.
Just not in "binary". Even so, each "state" has a unique code and I can do Octal --> Hex in my sleep.
Annnd ....there are a couple of duplicates or near-as-dammit... a feature, not a bug .. because the HP is the same.. but the run/balance cap summation differs a tad.
Do the "truth table" and sub-in the "summed" HP as if building a threading chart:
....back shortly.. have to go find the chart in a "postable on PM" graphic format.
Meanwhile, two idlers is very useful, if only because vexatious
starting issues are minimized. LOAD as well as idler itself.
Ex: NONE of my loads have clutches. ALL are run at light loads. So I need a boost for starting, but much less once up and running.
Three idlers usually makes more sense than four
if you are making chips.
Chips are not my main goal, here. BTDTGTTS.
I'd rather make
tests and do experiments in me old age. If the "many balance point" RPC or Phase-Perfect isn't close enough to Utility-Mains perfection? The MEP-803A IS.
Lemme go scout "which" hard drive and find that fool chart..
I try to NOT do "photos".
It tends to fry some people's tiny minds when they read too slowly to FIND the ones I
have posted!