Right now I am looking into something like this:
http://www.alliedelec.com/eaton-control-automation-an19gn0d5e045/70904386/
I need to verify that the specified FLA rating is total or per channel. It seems, like you may be saying, that I could use each of the 3 poles for Line for each motor. Not sure where N and Gnd come into play here from an NEC perspective. Must either be contact broken?

 

Meld, Max, 12, now myself, and most others, realize what standard practices are in this country, particularly in industrial environments. The reasons are numerous and logically sound. For simple bench top operation in a lab, a manually operated switch will function, but for actual installation of a safe and sturdy system, complexities immediately arise.

You could go to the facilities and operations maintenance people there at the school and ask to see a "motor starter" or even a "motor control center" in one of the equipment rooms. You will see items like that shown in the pic #12 posted. You should, or by now may, realize that the "thermostat" is not meant to carry a current and voltage anywhere near that required for this motor to operate, but is intended for use with what we're calling a "relay", but people that work with power and installation of this hardware call a "motor starter".

If 3 of these are to be used, and simultaneous operation is possible, physically large and robust equipment will be necessary to safely carry and control the power being required.

Think horsepower.

 

3 phase is advisable, with 3 relays (contactors), but, you actually could do 3 single phase motors with a single contactor, technically speaking.

If the motors are not all in close proximity and on a single piece of equipment however, codes like the NEC will require separate switches for each motor, and those must be in the power circuit.

 

Right now I am looking into something like this:
http://www.alliedelec.com/eaton-control-automation-an19gn0d5e045/70904386/
I need to verify that the specified FLA rating is total or per channel. It seems, like you may be saying, that I could use each of the 3 poles for Line for each motor. Not sure where N and Gnd come into play here from an NEC perspective. Must either be contact broken?

The link shows a contactor with a 600v coil!, it is a size 2 which will operate a 15hp 3 ph motor, (or a 1ph 7hp).
I would look at something like the Telemecanique range of DIN starters or contactors.
N does not have to be switched, it is optional.
Most 3ph contactors have a 3ph HP rating As I mentioned, if using a 3ph contactor you could get away with a 5hp contactor (size 1 or 0) if you use all three contacts to spread the load.
If using a single contactor for multiple motors then you would need a 10HP version, minimum.
You will also need a suitable O/L and fusing for each motor.
If reference to NEC means you are in N.A. then I suggest you get hold of a copy of NFPA79.
Max.

 

How do I determine what HP equivalent I would require for 3x5HP motors? These types of information are where I get a bit lost, in addition to the fear that I am missing any NEC compliance.

I am also concerned about a master power contact starting all motors at once (assuming I leave the branched toggle switch in the ON position for all 3 of them) since each motor's inrush current is rated at 140A. Heat at the generator terminals and that strong of a compounded inrush current are concerning.

 

There is still quite a bit missing as to how you want to control them and the equipment involved? individually or all at once? totally manual operation (P.B.) or automatic/semi-automatic?
If worried about inrush then one at a time would be the preferred way.
I see a control station set up with a stop/start P.B. for each motor, also if status is required then the on P.B. could be (green) indicator lamp/LED type.
As previous, a main disconnect, fusing for each, contactor/relay, O/L for each, low voltage control transformer if needed. etc.
Max.

 

The typical use case is running two of the motors. The third is a backup in the event of a failure. This will be manually operated just for simplicity. I agree, one at a time where we're not risking a massive inrush current surge. I know breakers are designed to tolerate inrush spikes, but I don't know if it's common practice to implement with that kind of spike. So far I'm understanding this will require a main disconnect, then an individual contactor or starter?, then a breaker or fuse system. It seems the O/L and thermostat relay input could be integrated on the contactor assembly depending on which I use. I think that's what gets the most confusing.

This system will be run by a generator, likely:
http://www.hipowersystemstraining.com/quoteGen/modelDocs/ELD_1.pdf

And the reason I'm asking all this is because I'll likely have to add a new or reconfigure an existing power distribution panel to fit my application.
http://www.hipowersystemstraining.com/quoteGen/modelDocs/ELD_1.pdf

 

I notice the enclosure supply shown has two Live and a neutral, is this a similar to N.A. where the N is 120v WRT each Live conductor?
Are you supplying a sub panel to this existing one?
Max.

 

it's gotten more complicated than it was was the thread started. 3 phase motors would likely be better. Single phase may actually make it more difficult.

In the few installs I was involved in, the electrician did all the work. The contact rating of the internal switch and whether is Normally Open or closed is a necessary piece of info.

If this were 3 phase, i might tell the electrican that I wanted 3 disconnects and there is a thermal switch that's rated for whatever. You can say I plan on controlliing the motors externally with logic in another control panel and you'd like the control power to be 24 VAC. If your going to use a PLC, 24 VDC may be more appropriate or some systems can use RS485, I believe.

I had them set up, so that they can be configured to drop out on a power failure or not. Three phase protection and auto-restart was common. Only one system needed a thermal. You can get starters that are electronic, but they do lack certain features. All the sizing is then done for you.

For your control panel, you might want the ability to turn on a motor and/or determine it's status. Having separate disconnects allows you to take one out of service for repair. You can also ask for monitored contacts (e.g. Is the contactor closed or open). Is it running is yet another story.

It seems like you don't have simple system here. A PLC might even manage the motors. In some systems when dual pumps are involved, they share an equal load. Sitting isn't good for pumps, so they alternate when they can.

Yea, you could put everything in one big panel. In fact we had one system that was feed by 200 A 208 three phase.

 

I'd go:
230V, 3ph, 125A feeder
1x enclosure
1x 125a 3p non-fusible disconnect switch, lockable, Interlocked with enclosure door
3x 3p fuse blocks or 70A I2T brkrs
3x 3p NEMA1 motor starter (or IEC eq)
-(a contactor with overload block)
3x 3 pos selector switch (H/O/A), illuminated (for "run" or "auto" indication)
1x 150va control xfmr w fuse blocks
1x indicator, yellow (for trip or manual indication)

Wire the internal motor thermostats in series with the control contacts of the overload blocks.

If 480V is available, use it instead, smaller feeder, starters and fuses.

Note: the selector switches will need contacts configured for your choice of operation and indicator light schemes. Indication is largely a matter of personal style or end-user preference.

 

Be certain to have a licensed electrical engineer evaluate your work. The legal liability involved here is astronomical if the machine is mis-designed and it hurts someone. Keep in mind that you must design for fault conditions that could happen in the system, such as power fail, momentary power fail, operator error, and any other unexpected faults. Also, there are now OSHA requirements for industrial systems that can injure personnel to have suitable safety systems to shut the equipment down if someone gets into somewhere where he shouldn't. This regulatory compliance can really add to the complexity of the system.