Installation of a Hitachi WJ200 VFD and changes to the control switches on a PM1340GT lathe

[mksj]

This is a review/discussion of the installation of a Hitachi WJ200 VFD and changes to the control switches on a PM1340GT lathe. The lathe was purchase as a 3 phase unit, the stock 3 phase motor was retained. The Jiuh Dah Electric (Taiwan) 2 HP motor is not inverter rated, the nameplate indicates it is 220V, 60Hz, 6.6A and turns at 1720 RPM. The motor is not large, and is a tight fit. It appears to be a Metric D90L frame, the motor housing measures ~10" in length and 7 1/4" in diameter. The stock motor shaft is an unusual spec of 3/4" by ~3". There is only 1" between the back motor fan guard and the lathe splash guard, and the motor diameter limits the belt adjustment range. Those interested in a possible inverter rated replacement motor, might look at the 2 HP Leeson True Metric D90L 169862-00 or the Marathon version 090LT17FH6326 which looks identical. Both of these have 24x50 mm shafts, so the stock pulley would need to be bored or replace it with a different one. Replacement 2 HP vector rated motors I checked where too long to fit without cutting off the rear shaft. That being said, most 2 HP inverter rated motors have a constant torque ratio of at least 10:1, and have a useable maximum RPM of 1.5-2.0X the base (60 Hz) speed for 1800 RPM models. TEFC (fan cooled motors) are limited at slow or high speeds by the fan cooling capacity. I currently use the stock motor over a VFD frequency range of 20-80Hz, so a usable lathe RPM range would be around 25-2250. Using the vector motor VFD setting , there is no cogging even at very low speeds, I am adding a digital RPM meter to provide the lathe readout speed.

So on to adding the Hitachi WJ200 inverter. Usually I hardwire the VFD controls directly to the inverter with shielded cable, and use limiter switches and a safety stop switch. In the case of the PM1340GT, I decided to have a bit more complex switch logic with safety interlocks. The front mounted switches were all replaced with higher quality lighted units, and have multiple switch contacts needed for the interlock logic/light control. As currently configured, the coolant is operated only when the forward/reverse switch is engaged. An emergency stop, power outage or end of travel switch deactivates the forward/reverse switch until the lever switch is placed back to the stop position. The stop position deactivates the forward/reverse switch/relays, and also sends a lockout signal to the VFD to ignore all other commands. The Jog switch deactivates the other controls except the emergency stop. The system logic is reconfigurable. All a bit over the top, but adds a bit of safety and made an interesting project.

I opted to replace the stock control board and reconfigure the electrical switching system. The main board is now 1/4" Electrical grade linen phenolic, with an attached DIN rail to mount a 24VDC 100W (PWM) power supply and 24 VDC, a voltage regulator is mounted to the board to provide 7.5V to the RPM readout. I used separate relays (see picture) to control the coolant system (9), forward (3), reverse (4), main power interlock (9, ) stop (6), and jog (7) functions. These are connected in a way to provide interlocked actions as well as VFD control. These all just fit in the control box. The connection wires are connected using screw terminals, they are color coded and labeled as to function and connection. A star grounding system connects everything. All controls and cables can be quickly disconnected, relays provide LED function status to verify the operation of the mechanical switches. The stock lathe light uses a 24V 50W incandescent bulb, this was replaced with a 9W 24V LED bulb. So much cooler and whiter light with less power load. The stock AC control transformer was 24VAC, ~100W.

The Hitachi WJ200 Inverter is mounted in the lower cabinet using L brackets, and also mounted is 20A main power switch. Switched power is set-up to provide 120/240V for the power supply/DRO/coolant system, 240V for the VFD. All power and shielded motor/control cables are routed through watertight bulkhead fittings in the back of the cabinet. All high voltage wiring uses ringed crimps to connect to the screw terminals blocks. The VFD is easily accessible if needed. I had installed VFDs in the past, but the Hitachi (industrial grade) VFDs have a wide range of functions and was bit frustrating at first to get to work correctly. You can program these functions from the VFD control panel, but I found it much easier (after getting the software to work) to do this via a computer. The software, nor a hardcopy instruction manual was provided with the WJ200. The USB driver and Program software is available from the Hitachi web site, one must install the programming control software AND the driver software before connecting the VFD. I initially could run the program, but could not connect via the USB. If you use Windows, after the software is loaded and the VFD is on, connect the USB cable, go to Devices and Printers and make sure you are connected to the WJ200.

Hitachi software is available at no cost from their site.
http://www.hitachi-america.us/ice/in..._drives/wj200/

Software:You must first install the PDN driver first before connecting your VFD
http://www.hitachi-america.us/ice/in...pro_smm_sss_sd

Then install the ProDriveNext 2.1.1 English
http://www.hitachi-america.us/ice/in...oftware_dload/

The WJ200 needed to be programmed before it would work, the basic functions are fairly straight forward but I found running the VFD via the software reset some of the terminal functions causing the VFD to stop accepting terminal commands. In the end, I printed up the Quick Reference guide Group F, A B, C, H and P name/functions pages, and noted the changes I wanted to make. I then would make a few changes, download them to the VFD and then test the system. This way I could isolate any problems/changes. I also downloaded the Yaskawa V1000 VFD manual, which I found had a better descriptions of some of the same functions.

So far everything seems to be working according to plan with one small glitch. I use the VFD to brake the lathe, it is set to 1 second and works well up to an RPM of ~1000. Beyond that the regenerative energy trips the inverter into an overvoltage error. This is not uncommon. There are other program settings that can be used to tweak this, but there is a lot of momentum in the system at the higher speeds. I will be adding a braking resistor 50 Ohm (500-100W), and add a switch to go to a longer 2 stage deceleration program for higher RPMs.

Pictures: Old and new front panel switches; Original control board; Main linen phenolic board/Din rail; Wired control board; Wired control board with motor; Cabinet mounted VFD/power switch; Up and running.

May the force (VFD) be with you.

 

[GA Gyro]

Thank you for starting this thread, lots of good information in your OP!
And the pictures are clear and well composed.

That DRO, is it a variation of the Eason 12 series which usually goes on mills?
Curious.

THX again for the well written and detailed post!

GA

 

[mksj]

Hi GA,

The Easson ES-12 is configurable to mill, lathe or grinder. I had assumed that the Easson ES-12 were universal and all came with at lease 3 scale inputs and was going to use the extra axis for the Tailstock DRO. Unfortunately, the version I was sent has only 2 scale inputs. Knowing that, I would have ordered the ES-8 for the lathe.

As a follow up to a replacement 3 phase motor for this lathe, other than the Marathon metric series, the Marathon E467 (145TTTN6835) looks to be a very good alternative http://www.electricmotorwholesale.com/MARATHON-E467.html . This is a TENV (non-fan cooled, so shorter) compact inverter rated 2 HP motor with a torque rating of 1000:1 (essentially 0 RPM to the base speed) and should maintain HP rating from its base speed to at least 3600 RPM. I might look into replacing my stock 3 phase motor with this Marathon motor in the future and getting rid of the belt speed changes.
Mark

 

[GA Gyro]

THX Mark!

I had not thought of a 3X DRO for a lathe... I was debating whether the 3rd axis would be for the tail-stock or the compound slide.
In thought, could not figure a reason to have a DRO axis on the compound slide.

I ended up not getting the single phase 1340GT Matt had... it was the last one he had in stock. My bad... drug my feet making the decision, and Matt sold it to someone... which is fair. I will have to wait until probably January for delivery of my lathe.

OTOH: My M932V/PDF (yes, a VS version of the 932: it has the head from the PM45CNC mill) is being prepped as we speak... hope it will be on the freight carrier sometime next week. A trip to GA should not be more than a week more.

THX again for starting this thread... will read your improvements as you do them. May ask for a parts list and wiring schematics later, when I am closer to getting my lathe.
Mounting the VFD in the cabinet and cutting a hole in the door... that was an ingenious move... kudo's to you!

GA

 

[zmotorsports]

Looks good Mark. Congrats on getting it up and running.

 

[mksj]

I had several requests for additional information on the software programming of the WJ200 on my lathe. I have attached two files for review, one highlights the VFD parameter changes I made for the PM1340GT lathe and the reasoning for those changes. These are based on using the stock 3 Phase motor supplied with the lathe, the WJ200-015S and an external brake resistor. The second PDF document is comprehensive and includes all the programming variables in a spreadsheet format, examples of how to use the software to program the VFD, and wiring examples. Your application may be very different, so review the instruction manual carefully.

Please note this is machine specific and only and example of what I used for this PM1340GT lathe. My control logic is much more complex as I use a separate 24VDC power supply and relays to switch the VFD controls, as well as other devices. Probably not necessary, but all commands by the relays send multiple commands to the VFD. So all run commands require release of a separate software stop command, and logic wiring only allows a specific set of run command to be sent to the VFD.

There are dangerous, lethal high voltages present, and incorrect programming could be very dangerous. If you are not familiar and qualified to do these type of installations, seek out an individual that is.

Others reviewing this with additional suggestions should add or open a new thread and can incorporate these files into their suggestions.

 

[mikey553]

Hi Mark,

Thank you very much for your comprehensive review. It will be very useful when time comes to install the Hitachi VFD for my mill (hopefully soon).

I still have a couple of questions. How did you routed the power wiring to VFD? Did you use any disconnect switch or maybe your 20A switch acts as one?

If I am not mistaken you said that power wiring between VFD and motor is shielded cable. Is it correct? If so, where did you get a shielded cable (probably 12 or 14AWG) and is it absolutely necessary? I understand the shielding requirement for the control cables, but not for power ones.

The Hitachi manual requires to install an AC reactor at the input side of the VFD in some cases. Please see that section below.

WARNING: In the cases below involving a general-purpose inverter, a large peak
current can flow on the power supply side, sometimes destroying the converter module:
1. The unbalance factor of the power supply is 3% or higher.
2. The power supply capacity is at least 10 times greater than the inverter capacity
(or the power supply capacity is 500kVA or more).
3. Abrupt power supply changes are expected, due to conditions such as:
a. Several inverters are interconnected with a short bus.
b. A thyristor converter and an inverter are interconnected with a short bus.
c. An installed phase advance capacitor opens and closes.
Where these conditions exist or when the connected equipment must be highly reliable,
you MUST install an input-side AC reactor of 3% (at a voltage drop at rated current)
with respect to the supply voltage on the power supply side. Also, where the effects of
an indirect lightning strike are possible, install a lightning conductor.

I would say that my power supply capacity (transformer?) is way more than my house service (200A). Inverter is rated about 24A single phase on the input. Do you think the warning is applicable in my case? I was told that every reputable VFD has a start-up circuit, which purpose is to limit the current spike at initial power up. I could not find such circuit in my VFD (WJ200-022SF). What is your position on this issue?

Thank you,

Mike

 

[mksj]

Hi Mike,

I used a 20A rotary main power switch that I installed at the lathe, this is for a 2 Hp motor. This provides power to the VFD and also the control circuits. Since this connects directly to a dedicated 30A breaker circuit, I do not have a breaker at the lathe. If you already have an internal breaker in your control box, then I would route the power to the main switch, breaker/fuse, and then to the VFD. The VFD is directly connected to the 3 phase motor.

I use shielded cable for the control circuits and between the VFD and the motor to decrease possible noise contamination. May/or may not be an issue, but I have seen some evidence of VFD output wiring noise effecting other wiring (albeit small). Since your are converting 1 phase to 3 phase, 14G wire is probably adequate for up to 3Hp between you VFD and motor. You not only need to figure the maximum running amperage, but the VFD maximum amperage (usually 150-200% of the maximum running amperage). Shielded wire in this gauge is a bit difficult to find in small quantities. These are some examples on eBay (I purchased from this seller).

http://www.ebay.com/itm/25-Helukabe...639?pt=LH_DefaultDomain_0&hash=item1e94adcf47
http://www.ebay.com/itm/25-LAPP-OLF...555?pt=LH_DefaultDomain_0&hash=item1e94ad751b
http://www.ebay.com/itm/10m-Helukab...819?pt=LH_DefaultDomain_0&hash=item1e94adcffb

Many individuals do just fine without using shielded cable on the motor and control circuits. It is advised, but not required, unless you have an issue (or long runs). In many cases people do not shield their lathe direction controls, the speed potentiometer should use shielded wire if remotely located. Only ground the cable shielded at one end, usually at the VFD or star ground.

You should not need to install a reactor on the input to your VFD. This is only used in extreme situations where noise issues are affecting other equipment on the mains side, it is not defacto required item. I would not worry about it.

VFDs are wired directly to your machine breaker or main power switch, one can use different types of input noise filter in-line if needed. There is no soft start to the VFD. I believe what you are mentioning is that VFDs have a soft start ability, so in the program settings I use the default 5 second ramp up to the designated frequency. The slope (acceleration) of this can be altered, but it is not an issue for use in a lathe. This reduces the start up amperage of the motor. There shouldn't be any other requirements.

Hope this addresses your questions.

Mark

 

[mikey553]

Hi Mark,

When you supply power to VFD after a long period of it's being off, a big current spike will flow to VFD to charge the capacitors. In this initial moment the capacitors will act as a short circuit. Unless limited one way or another this current spike can damage the VFD components. I was told that some of the VFDs include a special resistor, through which the current flows during power up. After capacitors are charged the resistor gets bypassed by some kind of relay.

This has nothing to do with soft start of the motor and noise issues. It is about protecting the VFD itself. Please read the Hitachi warning (in blue color) one more time. Do you think it is applicable in our case? Do you frequently switch the power to VFD on and off with your 20A rotary switch?

Mike

 

[JimDawson]

If you have normal size wiring, in this case probably #10, with a 30 amp breaker, powering the VFD then there should be no problem. The resistance of the feed wiring should provide adequate inrush protection, in effect, the wiring becomes the current limiting resistor. This inrush only lasts for a fraction of a second. The recommendations in blue really only apply to heavy industrial applications where you may have a very large main power buss feeding a number of VFDs and other equipment. Also, I almost never turn my VFDs off.