Correct voltage input fried VFD?

Sam4886 · Mar 19, 2018

I am pretty new to VFDs. Got my first one in today to put on an old drill press that Im converting to 3 phase so I can use the speed control on the VFD.

Here is my problem... I hooked it up to 120v power, heard a pop, and smoke started rolling out. Voltage verified by meter.

The VFD is a teco westinghouse L510-101-H1-U. 120v single phase input, 1 HP rated. Output is 220v 3 phase.

Motor is 3 phase, 208-220 or 480, 3/4 HP.

I cut a 3 prong extension cord and hooked the ground to ground on the VFD, then the black to the L1(L) and white to L3(N).

What am I doing wrong here? My VFD is smoked so I'll need another one, but some guidance would be great.

JLarsson · Mar 19, 2018

What connections did you make on the motor side? Are there any bare wires that could have contacted the case and shorted out on either side (VFD power supply or motor control)?

Sam4886 · Mar 19, 2018

No bare wires. Connected the motor to the VFD via 3 wires per the directions on the wiring plate. Just went lead 1 to 3 from left to right in the last 3 slots. My understanding was that the order doesn't matter except for rotation direction.

The motor wasnt and isn't grounded. Planned on adding that later after testing.

JLarsson · Mar 19, 2018

Did you apply power to the VFD without having the motor connected? How is the VFD mounted? Just to be clear, you hooked the ground wire from the power cord to the ground terminal at the bottom of the unit? Was the VFD used or new?

Sam4886 · Mar 20, 2018

It was a brand new VFD ordered from MRO supply.

The motor was connected before anything was plugged into power.

The vfd was laying on a bench next to the drill press for testing, the motor is mounted on the DP already.

Yes, the ground was run to the grounding screw. On this VFD, the ground is a couple inches below the rest of the connection points.

JLarsson · Mar 20, 2018

Hopefully, someone else will chime in here. The only other thing I can think of is the motor not being grounded to the VFD (really should have been, I think) caused an issue somehow.

And then one other thing comes to mind. What happened to the original power cord for the DP? Did you maybe leave it hooked up to power a light or something?

rons · Mar 20, 2018

Sam4886 said:
I cut a 3 prong extension cord and hooked the ground to ground on the VFD, then the black to the L1(L) and white to L3(N).

What am I doing wrong here? My VFD is smoked so I'll need another one, but some guidance would be great.

What size circuit breaker was on the input of the VFD?

Where there any fuses? Fuses should be used for short circuit protection. Sounds like you learned that one the hard way.

Arrange to return the VFD. They fail sometimes and a reputable seller will be able to cover your bet.

I use the word "bet" because of the nature of the product....

JST · Mar 20, 2018

Teco are usually OK from all I have heard.

The model number checks out as correct.

Could there have been any stray wire strands that got away and touched things they should not have?

If you had the thing fail immediately when power was applied, then the issue is not with the motor, since you had not tried to run it yet. May be a defect.

Sam4886 · Mar 20, 2018

I'm pretty sure the circut I was using is on a 20 amp breaker. I'll look when I get home.

All original wiring was removed from the DP. All the connections I made were either taped well or got heat shrink, so I don't think anything contacted and shorted.

I've already got a return started, we'll see how that goes.

A couple additional questions...

A fuse wired in should be a 120v inline between the outlet and vfd, right? Would that have saved the vfd with the power being 120 already?

For grounding, can I just run a ground wire from the motor case to the vfd? There's no provision for an original ground on the motor. I'm thinking just hook up to one of the screws for the electrical box cover.

ignator · Mar 20, 2018

Assuming you didn't damage this via a wiring error, I'm guessing it's the voltage doubler circuit used to boost the 120 to 240 needed for the motor operation. I can see infant mortality as a possible failure, most likely a shorted capacitor, that then smoked other components.

mksj · Mar 20, 2018

Wiring is correct, even with a shorted output or bad motor the VFD protection circuit should have kicked in with an error message. If the input wiring was shorted the breaker would trip. Most likely a random component failure, as others have mentioned would return it for a replacement unit. They tend to be reliable units at the price point, you can see failure of VFDs that have not been powered up for a long time (i.e. sitting on the shelf for a year or more).

rons · Mar 20, 2018

Sam4886 said:
A couple additional questions...

A fuse wired in should be a 120v inline between the outlet and vfd, right? Would that have saved the vfd with the power being 120 already?

Rhetorical Question:
question asked in order to create a dramatic effect or to make a point rather than to get an answer.

Depends on what fails. Short-circuit protection is about all you can do from the outside. If the inside of the box is designed as to save the very last Yuan then you are screwed. I don't care for those Teco cheapos. It's a crime to tack on the Westinghouse name.

Jraef · Mar 20, 2018

Sam4886 said:
...

I cut a 3 prong extension cord and hooked the ground to ground on the VFD, then the black to the L1(L) and white to L3(N).

There is a slightly ambiguous issue with this in their manual, vs the photographs in their manual. In the manual, they say that for a single phase input, the L2 terminal is removed and to connect to L1 and L3 as you said you did. But on the photos of the unit, they show the two line terminals as being marked L1 and L2, with the center terminal missing. So did yours have 3 terminals and you connected to only two of them, or did yours only have two terminals?

Sam4886 · Mar 20, 2018

That wasn't meant to be a rhetorical question. Like I said, I'm far from an electrician. I think I understand how the fuse should be wired, just looking for confirmation.

rons · Mar 20, 2018

Jraef said:
There is a slightly ambiguous issue with this in their manual, vs the photographs in their manual. In the manual, they say that for a single phase input, the L2 terminal is removed and to connect to L1 and L3 as you said you did. But on the photos of the unit, they show the two line terminals as being marked L1 and L2, with the center terminal missing. So did yours have 3 terminals and you connected to only two of them, or did yours only have two terminals?

From manual:
Note: Screw for terminal L2 is removed for the single phase models.

rons · Mar 20, 2018

Sam4886 said:
That wasn't meant to be a rhetorical question. Like I said, I'm far from an electrician. I think I understand how the fuse should be wired, just looking for confirmation.

The manual says:

The L510 inverter is an electrical / electronic product and must be installed and handled by qualified service personnel.

I'm sure that the only people they sell these things to are electricians. :nutter:

If you can get your money back now is the time to ask. Or take your chances with another.

MattiJ · Mar 20, 2018

Sam4886 said:
A fuse wired in should be a 120v inline between the outlet and vfd, right? Would that have saved the vfd with the power being 120 already?

Fuses won't help much with the smaller VFD's
These are typically not repaired, only replaced with completely new one so it doesn't matter much if the single faulty component "kills" everything else also in the havoc.

Correct fusing could be relevant for fire hazard tough.

Jraef · Mar 20, 2018

rons said:
From manual:
Note: Screw for terminal L2 is removed for the single phase models.

Right. But that doesn't jive with the photo, which shows that the 2nd terminal is removed, but the 3rd terminal is marked L2, not L3. The reason I bring it up is because it may point to a mis-labeled unit. the part numbers jive with it being a 120V input unit, but the terminal numbers might be that of a 3 phase input unit, which would be a 240V unit.

rons · Mar 20, 2018

Jraef said:
Right. But that doesn't jive with the photo, which shows that the 2nd terminal is removed, but the 3rd terminal is marked L2, not L3. The reason I bring it up is because it may point to a mis-labeled unit. the part numbers jive with it being a 120V input unit, but the terminal numbers might be that of a 3 phase input unit, which would be a 240V unit.

Right, Right. But what do you trust, the manual drawing with text or the picture?

If the poster's unit has only two terminals then it does not matter. There is no choice but to connect two wires (110v) to two terminals. If the unit was built incorrectly then it will be easy to spot by the return department.

Fuses are ALWAYS good insurance, especially for newbies.

JST · Mar 20, 2018

One way to kill many VFDs is to wire backwards.... i.e. mistakenly wire power to the motor side. Some will not be killed by that, I happen to know (never mind how) that smaller Invertek units may survive that.

Lots easier to do that if both sets of wires are 3 wire. I assume the OP is positive that did not happen,

Correct voltage input fried VFD?

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