Automated Parking System

[an_kore]

I am currently looking at an issue related to breaker tripping in an automated parking system. The breaker has been tripping on lifts that are heavily loaded. Although only two lifts have had this issue, I anticipate more as more spots become utilized. This typically happens about halfway up, where the motor shuts off and current through the system goes to zero. It can still function by resetting the fuse, waiting, and trying again. Source power is 1 Phase 25 amps 208V and motor is 3 Phase 230-277 Delta 400-480 Wye 50/60 Hz . I am wondering if the voltage difference is the cause of breaker tripping or could there be any other issues? For example VFD's not calibrated correctly, incorrect frequency, etc. The whole system including the motor is European made. I would really appreciate any input and will try to get more information on the system.

 

[Hv&Lv]

You have single phase 208 for a three phase 230-277Delta motor That can also be connected 400-480Wye.
that it?

 

[gadfly56]

^^^^ What Hv&Lv said. Running a 3-phase motor on single phase, at voltage waaaaay lower than expected; I'm amazed that the motor hasn't gone incandescent and launched itself. If the machines ever rebel, this one's going to be leading the charge.

 

[MD Automation]

I assume that the OP has a single phase 208VAC supply feeding a VFD, which in turn powers a 3 phase motor. This is OK, providing the VFD is sized correctly (its output would be de-rated for the single phase supply). And if the motor is wired for Low Voltage (Delta), then it should also be OK…unless the design had the motor spinning at full rated rpm and utilizing near full torque. With the 208 VAC supply instead of 230, the VFD’s DC bus output will be slightly lower. This in turn affects the top speed the motor can hit before it goes into “field weakening”. But again, if there was any headroom in the original design it should be fine.

You indicate there is a breaker tripping, is this the breaker feeding the VFD? I ask because you then mention resetting a fuse?

Is this problem new and the system been in place for a long time? Or are the lifts recently installed?

Is it possible that the overall design is good, but somehow the breaker supplying the VFD was spec’d incorrectly for the install? Have you placed an amp clamp on the supply conductor to see what the VFD draws under load?

You say the lifts that trip are heavily loaded. Are they by chance over-loaded?

 

[hbiss]

I think he said that there was a VFD in there someplace.

-Hal

 

[Hv&Lv]

I assume that the OP has a single phase 208VAC supply feeding a VFD, which in turn powers a 3 phase motor. This is OK, providing the VFD is sized correctly (its output would be de-rated for the single phase supply). And if the motor is wired for Low Voltage (Delta), then it should also be OK…unless the design had the motor spinning at full rated rpm and utilizing near full torque. With the 208 VAC supply instead of 230, the VFD’s DC bus output will be slightly lower. This in turn affects the top speed the motor can hit before it goes into “field weakening”. But again, if there was any headroom in the original design it should be fine.

You indicate there is a breaker tripping, is this the breaker feeding the VFD? I ask because you then mention resetting a fuse?

Is this problem new and the system been in place for a long time? Or are the lifts recently installed?

Is it possible that the overall design is good, but somehow the breaker supplying the VFD was spec’d incorrectly for the install? Have you placed an amp clamp on the supply conductor to see what the VFD draws under load?

You say the lifts that trip are heavily loaded. Are they by chance over-loaded?

that’s kinda what I was getting at... the 208 will give him 294 once it gets chopped up, but there are lots of unanswered questions in his post. Lots to assume with his situation. We need some more information really...

 

[hillbilly1]

I ran three phase over to a new elevator at a church, what did they do? They bought a single phase elevator with a vfd to convert it back to three phase! So my feed was too small, and had to run a new bigger line 230 feet!

 

[Jraef]

If I had to guess, I’d say the problem is that, being a European design, the motors are designed for 230V 50Hz. But you only have 208V available So unless the programming of the system limits the speed to 90% (208/230), the motors will lose torque at the square of the voltage difference, meaning your motors will only develop 81% of rated torque. If the system loading was too close to the bone, the motors will stall more easily. The Europeans frequently don’t account for 208V because they don’t have it over there.

But going back and reading your original post, it would be much more likely that the VFD would be tripping, not the breaker. It’s possible that your breaker is too small.

 

[an_kore]

I assume that the OP has a single phase 208VAC supply feeding a VFD, which in turn powers a 3 phase motor. This is OK, providing the VFD is sized correctly (its output would be de-rated for the single phase supply). And if the motor is wired for Low Voltage (Delta), then it should also be OK…unless the design had the motor spinning at full rated rpm and utilizing near full torque. With the 208 VAC supply instead of 230, the VFD’s DC bus output will be slightly lower. This in turn affects the top speed the motor can hit before it goes into “field weakening”. But again, if there was any headroom in the original design it should be fine.

You indicate there is a breaker tripping, is this the breaker feeding the VFD? I ask because you then mention resetting a fuse?

Is this problem new and the system been in place for a long time? Or are the lifts recently installed?

Is it possible that the overall design is good, but somehow the breaker supplying the VFD was spec’d incorrectly for the install? Have you placed an amp clamp on the supply conductor to see what the VFD draws under load?

You say the lifts that trip are heavily loaded. Are they by chance over-loaded?

Thanks a lot for your response. Yes, there is a VFD that powers the motor. The breaker that is tripping is the overcurrent protection at the lifts and not the one before the VFD. This is a new-ish system, just a few months old.
I'll try to get information on the breaker supplying VFD. Due to covid-19 I have not been able to visit the site and I have never worked with such systems before.
Lifts are not over-loaded as they are double wide and designed for 2 cars (max of 6 tons).
My guess was that the voltage difference between the supply and motor is causing an increase in current and tripping the breaker. Feeder wire size is 14 AWG and branch circuits are 12 AWG and the breaker that is tripping is 20 amps.

 

[an_kore]

You have single phase 208 for a three phase 230-277Delta motor That can also be connected 400-480Wye.
that it?

Yes

 

[an_kore]

I ran three phase over to a new elevator at a church, what did they do? They bought a single phase elevator with a vfd to convert it back to three phase! So my feed was too small, and had to run a new bigger line 230 feet!

What wire size did you use?
Thanks

 

[an_kore]

that’s kinda what I was getting at... the 208 will give him 294 once it gets chopped up, but there are lots of unanswered questions in his post. Lots to assume with his situation. We need some more information really...

I would really appreciate if you could elaborate on what information I should be chasing? I am trying to get more information on VFD specs, breaker feeding the VFD and single line.

 

[hillbilly1]

What wire size did you use?
Thanks

I can’t remember now, that was about 10 or more years ago, but the three phase spec’s took a 30 amp feed, while the single phase had to be bumped up to 60.

 

[an_kore]

In addition to all the above responses, I have received following information which is attached.

 

[an_kore]

I can’t remember now, that was about 10 or more years ago, but the three phase spec’s took a 30 amp feed, while the single phase had to be bumped up to 60.

They have run 14 AWG and 16 AWG for the most park and breakers are 20 amps

 

[an_kore]

Would you guys recommend any of the following fixes? Or could you tell why these may or may not work.
1. Changing the motor to the one that would meet the feed's 208V 60 Hz
2. Replacing the 20 amp breakers (ones which are tripping) with a 30 amp breaker and changing the wire from 14 and 16 AWG to 12 AWG
3. Installing a step-up transformer before the motor to bump up the voltage to 230V

Any feedback is appreciated

 

[GeorgeB]

The breaker that is tripping is the overcurrent protection at the lifts and not the one before the VFD.

Jraef, do you interpret this as in the VFD output? NOT a good idea. You have furnished several references in the past. If the breaker is a current sense and trips the input breaker or a control signal to the VFD, fine.

 

[hillbilly1]

They have run 14 AWG and 16 AWG for the most park and breakers are 20 amps

That small? May be a voltage drop issue. How long is the wire runs?

 

[an_kore]

That small? May be a voltage drop issue. How long is the wire runs?

From source it is about 50 feet and from control panel of each lift to the lift itself is only about 15 feet

 

[an_kore]

Correction to my previous statement, the breaker that is tripping is the one that is feeding the VFD. Both breakers are inside the control panel at the lifts. The VFD breaker is 20A, while the other is 4A. The 4A breaker does not trip.