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Thread: Choosing the correct VFD
11-17-2011, 12:58 AM #1
Choosing the correct VFD
I'm new to VFD's so I just wanted to make sure that i'm getting the one that I need. I recently purchased a Bridgeport mill:
It's an older style with the pancake motor and I will be running it off single phase 220V. The motor is 3-phase and wired for 440V so i'll be rewiring that to 220V 3-phase.
Here's the motor ID plate:
I started a thread to get as much info as I could about the mill and someone suggested this VFD. It's for 1-phase 220V in/3-phase 220V out and for a 1hp motor. A few posts after that was posted someone mentioned getting a VFD good for 2hp. Do I need a higher horsepower VFD for what i'm running? I plan to wire up a plug (I have a 60 amp outlet for my TIG, can't use both at the same time, so I won't have to drop a new line), to the VFD, then directly to the motor. I'd like to run a setup like this to control the on/off and speed of the motor. I am ready to purchase a VFD but I just want to make sure I get the right one the first time.... Any help or suggestions are gladly appreciated!
11-17-2011, 03:58 AM #2
NO NEED TO GET A BIGGER VFD..
Only time you need an oversize VFD, is if it is a 3 phase rated input model, and you are supplying single phase instead.. many lower power VFD's (under 3 hp models) are rated for single OR 3 phase input..
VFD's have short time overload capability built in.. Exact sized RPC's and static's do not..
If VFD is rated for 1 hp 115 v in, and 220 v 3 phase out. It will work PERFECTLY... You are driving a 1 hp motor..
Yes, you can get a 115v input, 220 v 3 ph out 1 hp VFD. Save 220 v circuit for a bigger machine... For example here : Adjustable Frequency Drive, Teco VFD, Phase Converter, Variable Phase Output
A 220 v in 1 hp drive, will also work PERFECTLY...
As will of course, 3 phase 220
11-17-2011, 07:18 AM #3
So not only can VFD's act as phase converters and give you variable speed but they can also step up the voltage too? Very interesting that I can use a standard 115V outlet to power the 220V 3-phase motor on my Bridgeport! Are there any drawbacks to using a 115V input vs. a 220V input? Out of that list you posted which model would be a good choice? Since i'm new to VFD's i'm not sure if there are better brands than others or if there are brands I should stay away from. Thanks for the reply!
11-17-2011, 07:44 AM #4
ESV152N02YXB from Vector Drive Plus, NEMA 1<br>Up to 40hp, Single/3 Phase<br>AC Tech SMVector (B) | Search All AC Drives | Marshall Wolf Automation, Inc.
Would be my choice. 208/240 poly phase in - 208/240 3 phase out. 2 hp rated to give you some headroom.
11-17-2011, 02:26 PM #5
NO HEADROOM OR OVERSIZING NEEDED PERIOD.
Advantage to running a 110 v 1hp VFD.. Power available throughout building..
No disadvantage at 1 hp level. Yes it steps up voltage..
A 1 hp motor DOES NOT DRAW ENOUGH CURRENT TO REQUIRE 220 v to feed it.. Many drill presses and home shop tools are 1 hp, and have run off of 110 v for decades... The OP stated he prefers to avoid 220 v, due to lack of circuits.. So he doesn't need to swap plugs or run only one machine at a time. Yes he could rewire 220 v circuit.. OR just plug small VFD into 110 v circuit..
Any big name VFD is fine... TECO, HITACHI, AC TECH, and others... The small TB WOODS might need an oddball fuse for input protection, if so stay away..
Posting an exact model does not make much sense.. They change constantly.. Just get a 110 v in, 220 v 3 phase out 1 hp VFD. Sensorless Vector is a nice option (will be listed in specifications of VFD), but not really needed on a 1 hp BP..
The VFD's have headroom built in for motor start up and short (~10 second) overloads..
See my above post.. for exceptions..
A VFD can actually run a LARGER motor than rated (within reason) ... But only up to the VFD's rating. SO... a 3 HP VFD will start and run a 5 hp motor (if it is lightly loaded on start.. like a tablesaw, drill press, or has a clutch..) You will only get 3 hp out of it, but many never use max hp of machine...
11-17-2011, 04:29 PM #6
Wasn't there something about some of these pancake motors drawing phenomenal amperage for their horsepower? It would be sensible to compare motor plate FLA with prospective vfd's available amps before ordering.
11-17-2011, 04:56 PM #7
That motor has a locked rotor code "J", according to my chart that is 7.1-7.99 x HP (in this case 1 HP) so your looking at 7.99 amp starting current, worst case. This of course is on the secondary side of the VFD, the primary side will see double that (if you are going with the 110V option) Soft starting and ramping the motor up will take some of the locked rotor load away, but it can never be completly eliminated.
11-17-2011, 05:03 PM #8
good point! amps is what these are all rated on.... so.... checking his posted nameplate picture...... 220v, 4.2 amps.....
checking model could quickly find, hitachi L100 1hp 120v in, 220 out - rated 4.0 amps
11-18-2011, 01:45 AM #9
Thanks so much for all the replys, lots of great info! Just to clarify it really doesn't matter to me which input voltage I use. You can't see it in my first picture but there is a 220V outlet behind the right handle of the table and there is a 115V outlet behind the left handle so I can use either. The 220V outlet is there for my TIG welder so i'll just have to unplug which ever one i'm not using so I can plug in the one I am using (which is fine since I can't run both at the same time). What are the benefits of the sensorless vector? There is a Teco without that and one with, in 115V input and 230V input.
MOD. FM50-201-OC, 230 VOLT SINGLE PHASE INPUT ONLY, 230 VOLT THREE PHASE OUTPUT, FULL 1 HP RATING, IP 20 ENCLOSURE - FACTORY NEW WITH MANUFACTURERS WARRANTY
1HP 230 Volt -- USE AS A PHASE CONVERTER PLUS GET VARIABLE SPEED, Model FM50-201-OC, Single Phase Input ONLY, Three Phase Output, variable frequency drive, variable frequency drives, ac drive, vfd, afd, frequency drive, drive, inverter, adjustable sp
MOD. JNEV-201-H1, 230V 1-PHASE INPUT/3-PHASE OUTPUT, SENSORLESS VECTOR, DRIVE AMPS 4.2 CONSTANT TORQUE, HEIGHT = 5.20, WIDTH = 3.03, DEPTH = 5.13, 3 LBS., IP 20 ENCLOSURE - FACTORY NEW WITH MANUFACTURERS WARRANTY
1HP 230 Volt -- USE AS A PHASE CONVERTER PLUS GET VARIABLE SPEED, Model JNEV-201-H1, Single Phase Input ONLY, Three Phase Output, variable frequency drive, variable frequency drives, ac drive, vfd, afd, frequency drive, drive, inverter, adjustable sp
11-24-2011, 08:16 PM #10
SENSORLESS VECTOR, DRIVE AMPS 4.2 CONSTANT TORQUE is preferred.
The constant torque are a bit more expensive but keep the speed the same under variable load.
The cheaper ones without constant torque are for fans and pumps where the load is constant and slowing down does not make much difference. It could be used for the mill but you might get some difference in surface finish.
I went with the constant torque for my lathe. When playing with it out of the box, I hooked it up to the 1 HP motor, turned it down to where it was barely moving, and tried to stop it by grabbing the pulley.
It just kept on pulling. I couldn't stop it.
One caution. If you use the VFD to run the mill slowly for a long time the motor will heat up because the fan on the motor shaft is not turning fast enough. If you want to do that, rig a fan to blow over or through the motor.
VFDs are wunnerful, wunnerful.
11-25-2011, 06:48 AM #11
its vector mode not CT that makes speed constant
sensor or sensorless vector mode is what keeps speed more constant under changing load. fans are indeed variable torque (VT) loads as their torque requirement is not constant - it goes down as the speed goes down.
both VT & CT v/hz (non vector) vfd's will operate a motor identically: speed will drop fairly linearly with load from synchronous speed (1800rpm) down to motor rated speed (say 1750rpm) at full nameplate load. so set that 1750 motor to 1800rpm before cutting, at 5hp load it will be going 1775, at 10hp it will be going 1750rpm. same for both types. set it to 50rpm no load then load it to 5hp and it will drop to 25rpm. load it it 10hp (30#-ft) and it will stop. Of course there are plenty of comp settings in these vfd drives today to help minimize this 50rpm variance due to load so in reality it prob can be only 5rpm change if these comps are used, making them very similar to sensorless vector mode at normal use speeds.
the designation in vfd's is supposed to take into account this lighter load at lower speeds. Time for a vfd designer (JST?) to hop in and tell us why the distinction; I see no design reason for the distinction other than perhaps the fact that at lower speeds and lower loads the PWM will have a lot lower on time, hence more need for the bus caps to supply higher current per pulse perhaps so they need beefing up. but that would mean VT drives would cost more, not less, so that's not it.... since at nameplate load both will supply same current to the same motor irregardless of type load, why should one be rated higher than the other? I have asked the Hitachi app engineers and they cannot answer this one. I've pushed and the result is they have to agree that one can run a CT drive to its VT higher current rating, so therefore there is LESS need to oversize a 1 ph input to 3ph only vfd drive. Example from Hitachi page:
WJ200-037LF Inverter, 200 volt, 3 phase, 5 CT (7.5 VT) HP, 17.5 CT (19.6 VT) Amps
So factory app guys had to agree that this 3ph only drive can run 1ph input upto 15hp motor, not the typical 10hp 2x rule of thumb limit. I actually think it is more a marketing reason than engineering reason - until someone can show me otherwise.
11-25-2011, 11:22 AM #12
It ended up going with the Vector drive unit from Teco, MOD. JNEV-201-H1, 230V 1-PHASE INPUT/3-PHASE OUTPUT, SENSORLESS VECTOR, DRIVE AMPS 4.2 CONSTANT TORQUE. Hopefully it shows up today so I can get it wired up.
11-25-2011, 01:17 PM #13
Saw this thread a bit too late; but your motor nameplate shows a Service Factor of 1.25; which puts you at over 5amps / 220 volts. This is a bit more than 1hp. You'll be able to use your 1hp VFD just fine; but I would suggest that others in this situation spend a few bucks more and go with a 2hp unit.
11-26-2011, 12:22 AM #14
Hopefully the VFD's 4.2 amps is enough.... Should I be concerned, possibly return it? I'm sure I can return it if need be because I don't want to run into problems now or down the road. Can you explain what effect the service factor has on the amps of the motor?
11-26-2011, 12:41 AM #15
11-26-2011, 06:38 AM #16
not sure why one would be interested in:
without overheating or otherwise damaging the motor if rated voltage and frequency are supplied to the motor.
Insulation life and bearings life are reduced by the service factor load.
reducing the life of one's motor by running in the overload area.... btw, vfd drives add some amount of additional heating to a motor by the unpure sine wave; the exact amount is determined by the particular vfd design; i would venture around 10% extra heat from these kind of drives. SF was invented before the vfd and I doubt it takes into account this extra heat either so a motor run to its SF on a vfd MAY actually overheat and fail after all. Just doesn't seem like a place to design a vfd to run a motor to.... I vote for your 4.2a drive being just swell.
11-26-2011, 10:30 AM #17
If you run the mill easily cutting and freely spinning you will have no problem as the motor and VFD are working at less than nameplate max.
Accuracy and finish will be much better also.
If you are doing a long difficult cut, keep feeling the motor and VFD, if VFD case is too warm to comfortably keep your hand on it, it is being strained.
Your motor is rated at continuous duty so the insulation is probably good for quite a bit of heat. Some motors have a heat rise rating on the plate. I have seen some that would severely burn your hand if you touched the case and still be within the temp rating.
11-26-2011, 11:08 AM #18
You've chosen a very good drive for that b'port application. You'll be pleased with the
Some random comments in no particular order.
1) I've bought 120 volt input drives for applications like this.
2) You could have upsized the drive a bit in the case that you ever got a 2 hp machine.
3) when you go to assemble the drive to the motor, remove the drum switch and set it
aside. The three motor power leads go directly to the terminals on the drive. Plus
the green ground wire of course.
4) it's best to put a small remote box where the drum switch used to be, with a toggle
switch (foward, off, reverse) and a small 5K variable resistor, in that box. This allows
you, with suitable programming, to control the drive from that point without having to
use the keypad or dial on the drive itself.
Resist the temptation to install tach displays, lights, extra switches, bells, buttons, etc.
11-26-2011, 11:26 AM #19
Upper Left Switch is for coolant
Upper Middle Switch is a 3-position rotary switch for REV - STOP - FWD control
Lower Right Knob is a 5K Potentiometer that controls speed of motor
We are running a 3HP Constant Torque Drive on a 2HP Lagun Motor - also fitted with a Dynamic Braking Resistor and is capable of stopping the spindle smartly. Works well for power tapping.
11-26-2011, 02:50 PM #20
"What is the fun in that? "
We don't need no stinkin' whistles or bells....