Pm 1340 Gt Vfd Question

[Dman1114]

I have the GS2 on my Grizzly g4003g... newly installed....

I didn't have a break resistor for a couple days ... was in the mail on its way. anyhow

i found it would stop the chuck from all speeds within 2 secs... if programmed... but at 1400 + Rpms with my 6" 6 jaw and a piece of 2 inch aluminum in the jaws. at anything under 1.8 sec breaking time it would over load and i would get an error....


Went on eBay and found me the proper size breaking resister for like 30 bucks....

now it stops at 1 sec no problems... and that is fast. I don't dare set it to stop any quicker.

Breaking resisters are cheap... no reason not to get one unless you don't need to stop fast.

 

[NoSquib]

I have the GS2 on my Grizzly g4003g... newly installed....

I didn't have a break resistor for a couple days ... was in the mail on its way. anyhow

i found it would stop the chuck from all speeds within 2 secs... if programmed... but at 1400 + Rpms with my 6" 6 jaw and a piece of 2 inch aluminum in the jaws. at anything under 1.8 sec breaking time it would over load and i would get an error....


Went on eBay and found me the proper size breaking resister for like 30 bucks....

now it stops at 1 sec no problems... and that is fast. I don't dare set it to stop any quicker.

Breaking resisters are cheap... no reason not to get one unless you don't need to stop fast.

Great! Thanks for sharing. Being as I do not actually have one in front of me to play with, it is great that you do and were willing to share the results. That should clear the murky water for us! And for what it is worth, I completely agree, when I worked at ______ company, we did not have a braking mechanism, and, at times, you simply stood back and waited for it to stop slinging parts/tools before you approached. I'm with you, when I order my lathe, I will have a braking (I think we've been crossing up the spelling ) resistor.

 

[Dman1114]

The GS2 manual is pretty good... I got some pointers from another member here.... but the manual tells you what size to get. I just got on eBay and searched for one that size.... 300w 70 ohm

i went with the 3hp GS2 here is a link to the resistor...

very easy to install...

just bolt it to the cabinet n plug and play 2 wires

 

[JPH]

I am putting a 50 ohm/500w braking resistor on my 1340GT and will use the programming of another member here to do a tw0-stage braking: Normal braking will be about 1 second, and this will be fine for the stock chuck at any speed and larger chucks like my PBA at slow speeds. When running my 8" chuck above 1000 rpm, I will engage the second braking algorithm which Mark as proven to stop the larger chuck in about 2-3 seconds.

That's very good to hear, since I'll be following in that direction. Your postings have been very helpful in my making up my mind. Keep up the informative posts. Thank you.

 

[JPH]

I have the GS2 on my Grizzly g4003g... newly installed....

I didn't have a break resistor for a couple days ... was in the mail on its way. anyhow

i found it would stop the chuck from all speeds within 2 secs... if programmed... but at 1400 + Rpms with my 6" 6 jaw and a piece of 2 inch aluminum in the jaws. at anything under 1.8 sec breaking time it would over load and i would get an error....


Went on eBay and found me the proper size breaking resister for like 30 bucks....

now it stops at 1 sec no problems... and that is fast. I don't dare set it to stop any quicker.

Breaking resisters are cheap... no reason not to get one unless you don't need to stop fast.

One second. Fantastic. Thanks for the specific info.

 

[mksj]

As others have outlined, a braking time of 1-2 seconds is feasible when using a braking resistor, I see no reason not to use one if your VFD dose not require a braking module (which can be expensive). Since there are different VFD inputs and programming, there are many possibilities how to program and engage different braking times. The bottom line, you can stop a chuck very quickly without having to jump on a foot brake. One must be realistic as to the stopping time as the speed and the weight increases. I can say that the WJ200 with the brake resistor, will stop a 60lb chuck at 1200+ RPM in about 1-2 second without fault. Some of the other VFDs will fault out, even with a brake resistor, so not all VFDs are created equal.

Low speed cooling of motors varies by type and how it is made. A heavy cast iron motor with higher temperature insulation can tolerate more extreme operating ranges. With a manual lathe, you are not operating the motor at full load continuously, so overheating is unlikely with a well built motor. Still heat will shorten a motors lifespan, the question is will it be an issue in your case. Most likely not. Some motors include thermal switches that can be connected to the VFD and will cause a fault. A TENV motor will run cooler at low speed.

Below is a comparison of heat build up at different VFD frequencies for Marathon motors of various enclosures. The graph would infer that TEFC can run at fairly low RPMs and still be in a safe operating temperature range without external cooling. This mostly applies to newer motors with higher temperature ratings for their insulation. If you have a 6 speed gearbox version of the PM1340GT, I can see no reason to operate it at very low Hz under high load for an extended period of time. This probably is a bigger issue with 2 speed range lathes that usually operate the VFD/motor over a 10 fold speed range. In many cases the motor is oversized.

 

[NoSquib]

Stumbled across this tonight. Good one that will answer some questions here.

 

[stevemetsch]

If you buy the 3 phase PM1340GT, you only have the expense of the VFD and a few electrical components to convert it, so maybe $250 in total. Although the the Hitachi WJ200 is what QMT usually bundles with the machine, something like the TECO JNEV-202-H1 will work just fine and they run about $180. http://dealerselectric.com/JNEV-202-H1.asp

The PM1340GT motor space is very compact, so replacing the stock 1 phase motor with a 3 phase, you have very few options and will at least double the cost. The conversion to VFD is not necessarily difficult, there are different options of how to implement it. Some people keep the stock 240VAC to 24VAC transformer to power the light, but remove the contactors, relay and board wiring. You retain the wiring to the direction controls. You install a single 4 pole relay on the main board and wire everything up. See attached file with a suggested schematic and approximate parts costs. I would not use input 4 for 2 stage breaking, but others have requested it. The VFD control connections are all low voltage, it does require some reconfiguration of the front panel switches which is easily accessed.

The motor is directly connected to the VFD, the VFD is connected to your main power and should incorporated a power disconnect switch/breaker which is usually through an enclosure or electrical sub panel. I use a 20A plug for my machine which comes off a dedicated breaker in my garage sub panel. So there is not really anything to break relative to the lathe. There are no other electronics on the lathe to damage. That being said, the motor/VFD/line power is high voltage (240V), so a basic understanding of proper wiring is required. You can also have an electrician review, and/or do the main power hook-up.

On the mill DRO, the ES-12 provides a few more graphical options for machining, but it comes down to cost.

Different info on the PM1340GT at this site and individual comments, so a very nice machine. I have had issues with the supplied chucks in the package having poor TIR and balance issues, you get what you pay for.

I just got my new PM1340GT in the shop and due to blissful ignorance exaggerated by optimism I have a 3/4 ton decoration until I get the VFD installed. I am looking for a simpler version of the schematic by mksj. Is it possible to run my 220V to the VFD and then the three wire+G to the motor.
Then run another 220V to one of the existing contacts that power up the 24V transformer. Use that 24V to power the existing controls and feed theitr "output" to the VFD.
I am not understanding why there is a NEW low voltage relay in the schematic.
I may just be cheap, but I don't like to have lots of parts left over because i HAVE to save them all.

 

[mksj]

I did consider this when I first was installing my VFD. The controls operate the two contactors. They also use another DC relay as a power start up relay. It just got a bit challenging figuring out all the wiring to get it to work correctly. It is possible to strip L1-L3 wires from both contactors and use one contact on the forward/reverse contactors wired to the VFD control circuit to control the 24VDC to the VFD inputs. The Jog is a bit problematical because it requires both a JOG command and a direction command to be inputted at the same time. So you would probably need to use a 2 pole switch on the front panel to operate the direction control contactor and a second independent switch to send a 24VDC signal to the JOG input on the VFD. Not sure how the rest of it will work, but I did something similar to this with the PM1340GT control board that I ended up using in in a bandsaw conversion to low voltage contols. I did another build trying to pass through the signal VFD 24VDC via contactors and they ended up being unreliable (not sure why, but they ran off of 120VAC). I believe it was an issue of getting the relay to latch correctly.

The single 4 pole relay is inexpensive, simple and works well, you strip out the contactors and origional 24VDC power relay. It only works in this configuration with the WJ200 because it can supply 24VDC at 100mA for the control inputs. The JNEV, will not work as well as most other VFDs. If this is what you have, you can try the contactors, I have also built relay control systems for others that use a separate DC power supply. You could reuse some of the controls switches and the transformer to power the light, but not the power indicator light because it draws too much current and you still need a speed control. There are a lot more control configurations possible when going to a dedicated 24VDC control system (I am doing a more complex version per their specifications for another forum member currently), but whatever works is fine at the end of the day.

 

[stevemetsch]

I did consider this when I first was installing my VFD. The controls operate the two contactors. They also use another DC relay as a power start up relay. It just got a bit challenging figuring out all the wiring to get it to work correctly. It is possible to strip L1-L3 wires from both contactors and use one contact on the forward/reverse contactors wired to the VFD control circuit to control the 24VDC to the VFD inputs. The Jog is a bit problematical because it requires both a JOG command and a direction command to be inputted at the same time. So you would probably need to use a 2 pole switch on the front panel to operate the direction control contactor and a second independent switch to send a 24VDC signal to the JOG input on the VFD. Not sure how the rest of it will work, but I did something similar to this with the PM1340GT control board that I ended up using in in a bandsaw conversion to low voltage contols. I did another build trying to pass through the signal VFD 24VDC via contactors and they ended up being unreliable (not sure why, but they ran off of 120VAC). I believe it was an issue of getting the relay to latch correctly.

The single 4 pole relay is inexpensive, simple and works well, you strip out the contactors and origional 24VDC power relay. It only works in this configuration with the WJ200 because it can supply 24VDC at 100mA for the control inputs. The JNEV, will not work as well as most other VFDs. If this is what you have, you can try the contactors, I have also built relay control systems for others that use a separate DC power supply. You could reuse some of the controls switches and the transformer to power the light, but not the power indicator light because it draws too much current and you still need a speed control. There are a lot more control configurations possible when going to a dedicated 24VDC control system (I am doing a more complex version per their specifications for another forum member currently), but whatever works is fine at the end of the day.

Thanks MKSJ,
I think this helps. I am understanding that I need to limit the VFD 24V to 100 ma.
So I need to use a separate power source for the work light (I can put a 120V to 24V xfrmr in line with a 120V wall plug ).
AND Change out the "Power" light to an LED that will work on 24V.
These two changes will let the VFD operate the controls except that the jog function may not work properly or will need to have a SPDT switch added to select Fwd or Rev.
If this is all wrong I will hire you to draw me a schematic.
BTW I have Hitachi WJ2000-15SF shipped with the lathe from PM and am plugging into 240V 1 phase.
Steve