How many hertz will a motor take?

The issue is safety, MECHANICAL and specific to that particular, bloody motor.

PISS OFFF !!!

....... Phil

First - from your specifications - as you know the speed on an INDUCTION motor is dependant on frequency not voltage for the RPM, yet you show the RPM higher with higher voltage . . . something wrong there.

Is this a two speed motor that can be wired for a different speed/voltage, or a bush type motor?

There are special applications where an induction motor with a lot of slip is normal, but not usually in conveyors, and not in that power range.

A three phase AC induction motor and you could probably do it. A single phase induction motor and you could probably do it. A single phase induction motor with a starting or running cap and it would smoke.

As long as the current is within reason and it is a three phase or single phase without capacitors, it should work. The motor may heat more with eddy current losses rising - and depending on the variable frequency drive may actually use less current/heat as the frequency increases - but you might want to monitor the heat if the motor is expensive to replace - but otherwise go for it.

Doubling the speed may be marginal - will the VFD actually put out 100 HZ? Nothing says you have to start off at double speed - increase gradually and monitor heat

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460 VAC is 60 Hz (USA)

to maintain full flux in the machine, the ratio of V/Hz must remain constant (aka scalar control). As you increase the frequency, the VFD outputs more volts. Eventually the VFD runs out of volts, so further increasing the frequency actually reduces the flux in the machine, leading to reduced power. This is called field weakening.

most SCIMs will happily run at 2x rated speed, but at reduced power (Torque falls off as 1/f^2) due to field weakening

as you increase speed, eventually one of two things will happen: the poower reduces to a point that cannot drive the load (try overspeeding a fan), or the rotor expands until it hits the stator (aka polling the machine). The latter is a bad thing, although it can be quite exciting to watch, especially with 600kW machines. Ensure you stand somwehere along the shaft axis rather than parallel to it, so if the machine runs away it doesnt get you.

Cheers Terry

I've been told that pulling the field wires off a parallel wired DC motor under power is also quite the bowel loosening experience.

I can imagine. ACCTs are equally dangerous.

A moderately common problem we used to have in our VFD test area (I used to design VFDs) was techs neglecting to turn the mains off before discharging the DC bus with a small tubular 50R DB resistor, which had DMM probes on the end of short leads, required 2 hands and pointed at your groin during normal operation. With the mains still connected, the bus wont discharge. Being DC, you cant pull off one lead, as an arc will form, short the DC bus and kaboom. The only recourse was to scream loudly, and get someone else to trip the E-stop thereby knocking off the power.

Cheers Terry

ACCT?

AC Current Transformer. c.f. DCCT (typ. hall effect).

Cheers Terry

ACCT

OK. No, never had much experience with those but I'm not about to run one with an open secondary.

its even more exciting if you try and open the secondary while its running ;)

Cheers Terry

One flash and you're ash!

yes, that most likely will work how ever, your motor may heat up.

Assuming it's a 3-phase motor, it'll run to 120Hz+

Bonfig also make their own Motor controllers/inverters.

If it's single phase it's probably easier to change the gearbox, it's only 4 small bolts and it'll slide straight off. Just make sure the flange is the right size. Speak to the dealer.

Single phase bonfigs run bloody hot anyway. :-(

- Steve

most little machines do. a favourable SA/V ratio means they are good at dissipating heat, so mfgs make then nasty (but cheap).

Cheers Terry

but 200F ??? I can't see that longevity is a concern.

- Steve

class F insulation is pretty standard, and thats rated for a LOT more than 93C

Cheers Terry