Powermatic 66 question....

[Ryan Brownell]

First time poster, long time LURKER and FAN of this forum! I just got a 1985 PM 66 with a 3 hp, 3 phase baldor motor wanted to see if any members have come across and similar "issues" I am having: the starter clicks quite a bit when starting up, I hear a high pitch noise coming from the starter relay (I think that's what it's called) when I ramp up my teco ac drive converter, and excessive burning on multiple test cuts with a miter gauge..... I was thinking that the voltage was off and affecting the rpm of the motor... Anyways thanks in advance for ANY help on this!

[Kirk Poore]

It sounds like what you're got is a Teco VFD converting single phase to three phase, then feeding the existing starter on the saw, which powers the motor. Is this correct? If so, you need to remove the starter. The VFD should not have anything between it and the motor--the VFD can be damaged if it's putting out power but there's not motor available. Assuming you have existing start/stop buttons for your starter (i.e., a magnetic starter NOT a manual starter) you should be able to wire your buttons to start the VFD.

If you have the VFD wired straight to the motor, I'm not sure what the clicking sound is.

The high pitched noise is probably the carrier frequency on the VFD. You can adjust this (check the manual for details). The default setting on my two TECO VFD's was high enough to create this sound. I altered the setting and the sound went away. I think they set the default to prevent interference with nearby electronics such as radios.

Kirk

[Dave Cav]

I don't know about the burning on your crosscuts with the miter gauge. Could be a blade issue (or the motor running backwards......) As for the starter/VFD issues, you do not need a motor starter with a VFD. The VFD replaces the starter, and VFDs will not be happy with any switching between the VFD and the load. The noises your are hearing may be due to the characteristics of the (more or less) synthetic 3 phase being fed out of the VFD into the motor starter circuits.

You could rewire your motor starter to operate on single phase and use it to turn the VFD itself on or off, but your motor start/stop control should all be done via the VFD, not the starter. If you want to use a remote start/stop switch you can use the aux control connections on the VFD.

I would take the motor starter off altogether and just run your single phase into the VFD, three phase out to the motor, and then if you want a remote switch, get a Grizzly 110 volt (NOT 220) paddle switch to wire into the remote start/stop terminals, or even a simple toggle switch. It's only switching low voltage, 12 VDC, I believe.

[Ryan Brownell]

Thanks for the info guys.... I had my friend who is an electrician help me out originally but it sounds like it's all wrong! What I have is this: The teco vfd is feeding a 3 phase outlet and I was plugging my saw directly into that. On my saw the power goes to the starter and there is another component in another box mounted on the saw under the motor cover which I thought was some sort of relay..... and that is the component making the high pitched noise. I'll take a pic tomorrow morning when I get to the shop.. Thanks again.

[Ryan Brownell]

wow.... I really had this wrong. Been doing more reading on this. My friend is going to get an earful...

[Dave Cav]

wow.... I really had this wrong. Been doing more reading on this. My friend is going to get an earful...

Don't be TOO hard on him. I know a number of electricians and none of them have ever known about using VFDs as phase converters. Some of them are aware of them, in more or less general terms in industrial use where you have 3 phase in and out and they are used for speed control or load following, but apparently using VFDs the way we use them for converting single phase to 3 phase is not very common in industry.

[Van Huskey]

Don't be TOO hard on him. I know a number of electricians and none of them have ever known about using VFDs as phase converters. Some of them are aware of them, in more or less general terms in industrial use where you have 3 phase in and out and they are used for speed control or load following, but apparently using VFDs the way we use them for converting single phase to 3 phase is not very common in industry.


I agree, we use VFDs for sorta an "off label" use.

[Kirk Poore]

wow.... I really had this wrong. Been doing more reading on this. My friend is going to get an earful...

VFD's are pretty much single-machine devices. This is because they can be damaged if they are powered up while not connected to a motor (so no switching on the fly), and because they can be programmed to limit the output so you don't overload the motor. That limit varies between motors, unless all the motors you're using the VFD on are the same size.

I don't know what that humming relay is, but it's quite likely you'll be able to remove it when you remove the starter.

Kirk