xfmr stiff enough... Elevator soft starts - lights dim

[wyreman]

http://www.aesupply.com/pdf/Class72G_Instruction Guide1_01_21_20053-3.pdf
Controller manual. It can be wired for in-line but the given the size and voltage it looks like in-Delta as Jraef commented.

Ingineur, according to that manual it implies he's talking about hydraulic



There's really no escaping relative size effect. One seat for adult is one seat but there is nothing you can do to expect a six person personal craft to have the same steadiness as one of those Vancouver Island ferries when you jump around on it. Relatively speaking the 0 to 300A is huge for the size of transformer. If each circuit was a branch, the service size is like a set of seats setup for your party. The entire watercraft(transformer and the service it is supported) dictates stability. You could talk all day about how you can jump around on the ferry and feel like you're on a slab of concrete but nothing you can do to get the same stability on a small boat.

Single ended service from a small(load or service vs transformer size) transformer is the least stiffest compared to a large multi-point with multi-point feed.

regarding the load being too big for the xfmr...
we've doubled the xfmr bank
I did the calcs and we were within specs

but mostly:
don't have to worry too much about the BCA!!

The Solid State
Starter controls
the current during
the start and
provides overload,
current imbalance,
reverse phase,
single phase and
shorted SCR
protection. In
addition to those
faults, on power up
the starter will
check the motor
configuration.

awesome thanks!
http://www.aesupply.com/pdf/Class72G_Instruction Guide1_01_21_20053-3.pdf

 

[Cow]

Wyreman,

I think you need to convince the boss and the customer to fly Golddigger, Gar, and Ingenieur out!!

 

[gar]

170430-0935 EST

We are now at 103 posts.

1. There are tenants that see lights flicker when the elevator runs. Do all lights on all circuits always flicker at all times that the elevator starts to move? Do any not flicker, or flicker less? Do the lights sometimes not flicker when the elevator starts? At any other times than when the elevator starts do lights flicker?

2. This thread started on the question of whether the power company source was weak. This implies making measurements at the demarcation point between the power company and the customer. From the photographs this appears to be where the meters are located.

We have to assume that the only common impedance between lights and the elevator comes from the power company transformers, and the service lines from the transformers to the distribution area where the meters are located.

The power company source appears to be a wye from three separate transformers. No way to know how the primaries are wired. Thus, there really are three separate 120 V single phase sources that happen to have a synchronized phase relationship to each other. Also it is reasonable to assume 0 impedance feeding the transformers.

Individual single load tests from a hot line to neutral can give us an estimate of the source impedance of that particular phase. This means measuring the change in voltage and the corresponding change in current from just before the ltest load is applied to just after, then Zsource is approximately Vchange/Ichange. The absolute voltage is not of concern, and therefore neither is the minimum voltage. One can estimate the line and transformer impedances, add them, and then compare the calculaed source impedance with the measured source (internal) impedance.

The source impedances for the three phases should be moderately close together.

3. Three 120 V light bulbs were connected from the three phases to neutral at the main panel. What was visually observed when the elevator started? Did all three flicker at the same time? Was the amount of flicker the same for each bulb? Was the amount of flicker the same for every elevator start? Do tenants see more or less flicker at their location, than at the main panel? Is flicker extremely quick, 100 mS, or longer, 500 mS?

4. When using min-max measurements in this type of test the measurement needs to be started just before the load change occurs, and ended just after the load change. So RESET just before load change, then immeadiately after the load change readout min and max.

Can information and values from yesterday for these various points be provided?

.

 

[gar]

170302-1246 EST

A suggestion if you can have it done.

There are apparently two sets of feeder wires from the power company transformers to the main distribution point where the meters are, and there are many meters.

Probably one meter for the elevator and possibly some common circuits for halls and hall lighting.

One set of feeder wires is smaller than the other. Have the power company split these two sets apart. Use one set to feed the elevator meter. Everything else, all other meters, are supplied from the other feeder set.

Now the only common impedance between tenants and the elevator is the transformer impedance.

If there are roadblocks, then try to work around them. This will reduce light flickering. If flickering is still too great, then elevator starting current has to be reduced.

.

 

[wyreman]

We are now at 103 posts.

1. There are tenants that see lights flicker when the elevator runs. Do all lights on all circuits always flicker at all times that the elevator starts to move? Do any not flicker, or flicker less? Do the lights sometimes not flicker when the elevator starts? At any other times than when the elevator starts do lights flicker?
THE FLICKER HAPPENS AT THE MAIN.
as far as I know ALL INCANDESCENT LIGHTS FLICKER every time THE ELEVATOR GOES UP.
I have seen the elevator cause the voltage to dip every single time it has gone up.
THE COMMENT ABOUT COUNTERWEIGHT AND MAX LOAD WAS VERY INTERESTING

2. This thread started on the question of whether the power company source was weak. This implies making measurements at the demarcation point between the power company and the customer. From the photographs this appears to be where the meters are located.

We have to assume that the only common impedance between lights and the elevator comes from the power company transformers, and the service lines from the transformers to the distribution area where the meters are located.
THERE IS A SOLAR SYSTEM ATTACHED WITH I PRESUME NET METERING, BUT THIS SHOULD NOT HAVE ANY EFFECT ?

The power company source appears to be a wye from three separate transformers. No way to know how the primaries are wired. Thus, there really are three separate 120 V single phase sources that happen to have a synchronized phase relationship to each other. Also it is reasonable to assume 0 impedance feeding the transformers.

Individual single load tests from a hot line to neutral can give us an estimate of the source impedance of that particular phase. This means measuring the change in voltage and the corresponding change in current from just before the ltest load is applied to just after, then Zsource is approximately Vchange/Ichange. The absolute voltage is not of concern, and therefore neither is the minimum voltage. One can estimate the line and transformer impedances, add them, and then compare the calculaed source impedance with the measured source (internal) impedance.

The source impedances for the three phases should be moderately close together.
I CAN DO MORE DELTA V WITH P-N 40A LOAD
Load tests begins typically with 6a per leg and then I toggle in a 40a P-N load instantaneously
https://1drv.ms/i/s!AkuU8mYuf3eEgVbEZrpB0QU9AQRz
Measured VDelta WAS 2.2; 2.14; 1.25 - so one leg was about half the change of the others!
CAN REPEAT THE MEASUREMENTS WITH EXTRA ACCURACY TO CONFIRM

3. Three 120 V light bulbs were connected from the three phases to neutral at the main panel. What was visually observed when the elevator started? Did all three flicker at the same time? Was the amount of flicker the same for each bulb? Was the amount of flicker the same for every elevator start? Do tenants see more or less flicker at their location, than at the main panel? Is flicker extremely quick, 100 mS, or longer, 500 mS?
FLICKERED ALL AT THE SAME TIME
INTENSITY VARIES: I SAW "A" LEG AS GETTING DIMMER, COLLEAGUE SAW THEM AS SIMILAR
REMOTE LOCATION UNK- PRESUME WORSE BECAUSE OF FEEDER DROP
I can go up to the furthest unit to measure minimum or delta V if needed.
Not a short FLICKER, MORE LIKE 500MS

4. When using min-max measurements in this type of test the measurement needs to be started just before the load change occurs, and ended just after the load change. So RESET just before load change, then immeadiately after the load change readout min and max.

Can information and values from yesterday for these various points be provided?
WE DID THREE TESTS PER PHASE WITH THE MINI LOAD BANK
MIN MAX
CRUDE LOG HERE
https://1drv.ms/i/s!AkuU8mYuf3eEgVbEZrpB0QU9AQRz

3LIGHT TESTS VIDEOS HERE
https://1drv.ms/f/s!AkuU8mYuf3eEgVqZj62jhqPsrp74
but only the 500ms duration is really clear.
The lights dip pretty good.
P-N voltage at the remote elevator disco was down to 104V

 

[wyreman]

that is really smart!

that is really smart!

170302-1246 EST

A suggestion if you can have it done.

There are apparently two sets of feeder wires from the power company transformers to the main distribution point where the meters are, and there are many meters.

Probably one meter for the elevator and possibly some common circuits for halls and hall lighting.

One set of feeder wires is smaller than the other. Have the power company split these two sets apart. Use one set to feed the elevator meter. Everything else, all other meters, are supplied from the other feeder set.

Now the only common impedance between tenants and the elevator is the transformer impedance.

If there are roadblocks, then try to work around them. This will reduce light flickering. If flickering is still too great, then elevator starting current has to be reduced.

.

Dawg! that is really smart!!
Let me see what I can do!!!

Wow
Id need a 2nd disco for the elevator line and untangle the house panel from the 1st bus.
too bad we can't see if that would help first before doing it..

I guess I could open all the other loads at the main and just keep the elevator shunt as the only load
do that first if that would help

I wonder if I should switch off all the house breakers and see if that helps.
The garage is full of car lifts where the cars are stored on top of each other - I think they're all on the house panel

 

[Bugman1400]

So what were the results of the flicker study? Once you have that, the standard solutions will work.

 

[wyreman]

here's the videos of the mini loadbank tests on the three legs
https://1drv.ms/f/s!AkuU8mYuf3eEgU_zG7szi5O8wyHE

I'll input the next iteration of the log in my handwriting next time!:angel:

 

[wyreman]

So what were the results of the flicker study? Once you have that, the standard solutions will work.

Inconclusive.
Operator error - sloppy measurement protocol.
Tried to do too much
Light bulbs were too subjective. No need to repeat

Mini load bank most interesting
120 [P-N] 40a instant loading needs to be focused on that one test
get very precise measurements showing the change in voltage and clearly attributed to each phase
Got to go back Tuesday

Elevator loading still shows "A"phase with biggest drop

Next session will be for the P-N loading

then ABC > BCA> CAB
Rotate the phases next time to see if the trouble follows the motor leads or the service wires.
More confident now that I see the controller manual has a phase monitor

 

[gar]

170302-1401 EST

wyerman:

There is no easy way to run the experiment.

At my home I have a 50 kVA pole transformer. This means the nominal current rating would be 50,000/240 = 208 A. The transformer is at the street, and from there to the pole where my heavy wires come to the house is a wimpy cable about 90 ft long.

At my main panel an about 10 A resistive load causes a change of voltage of 0.8 V. Thus, the total source impedance from my panel back to the primary lines is about 0.08 ohms. Thus, the wimpy line might be about #4. A 200 A load would cause my main panel 120 V to drop to about 104 V.

Using average voltage prior to application of a load and comparing with the minimum may not be the actual voltage change. From time to time my line voltage fluctuates a volt or so in a short time. So I really would like to know the voltage just before the load is applied, and then the voltage while the load is applied. For short durations, but not too short the min reading probably is a good estimate of the voltage during a short load dip.

I haven't run good tests on the min-max for the Fluke 27 and 87, but the response time seemed longer than 100 mS.

If you could get at the power company transformer secondary terminals, then you could see the voltage change with the elevator load. This would be the experiment to estimzte how much improvement separating the feeders would achieve.

 

[wyreman]

the 289 Response time is the length of time an input must stay at a new
value to be captured as a possible new minimum or maximum
value. The Meter has a 100 millisecond MIN MAX response time.
For example, a surge lasting 100 milliseconds would be captured
but one lasting only 50 milliseconds may not be captured at its
actual peak value. See the MIN MAX specification for more
information.

I might also get the software http://en-us.fluke.com/company/press/289-287-firmware.html
It is 10x faster than the best my powersight 3000 can do

 

[Ingenieur]

I wish I could be there, very difficult to assess remotely

these machines typically have no counterweight, it's hydraulic
pump pressure to raise
orifice restriction to lower (hence no issues descending)

imho the controller is working
it would be nice if the guy would lower the current limit for testing purposes to the lowest setting 116% x 186 = 216 A just to see if it reduced the problem
although not recommended to go less than 200%, if it starts smoothly and accelerates with full load, lower is OK
the car travel seems slow enough, perhaps 10 ft/10 sec or 60 fpm

judging from the service conductor current imbalance I would start there
but honestly, I do not think it is a supply issue, I think it is marginally sufficient
xfmr fla ~400 A
you are going to ~80% of capacity (>300 A) in a step change during starting, and get a Vdrop of 8-10%, that is not too bad (3-4% once stable and running, 25-30% (125/400) of xfmr rating)
although that 3-4% may be a bit much, if at 100% xfmr capacity (~400) A that translates to 11-14%

 

[gar]

170302-2044 EST

Ingeneur:

I believe the present transformers are each rated at 100 kVA and at a 120 V secondary voltage this is 833 A. This is the inphase secondary current, and thus line current rating. See post #1.


Wyerman:

If I go to my bench and run a Fluke 27 min-max test the results are:

My 1500 W heater resistive load which is about 10 A shows about a 4.1 V change which corresponds to a source impedance of about 3.1/10 = 0.41 ohms. At 35 A instead of 10 A this would be about a 14 V drop.

Changing my load to a 1/3 HP induction motor and using an oscilloscope I see a peak voltage change close to 20 V for a peak starting current of almost 50 A. Thus, about 0.4 ohms. Good correlation. The starting current remains this high for about 80 mS, and the voltage drop for this same time.

When using the Fluke 27 in min-max on motor starting I only get a voltage change of about 2.1 V. Much less than the actual 14 V. The 27 appears to be much slower than 100 mS. I don't have the 87 home, but when I checked it yesterday it did not appear as fast as 100 ms. Yet 100 mS is what the 87 is labeled at on its screen. I am sure your elevator motor is not starting in 80 ms.

I like your idea of getting Fluke software for your meter and recording the starting current.

.

 

[Ingenieur]

You're right 300 kva 120/208
At 208 800+ A
even less chance it's the xfmr capacity

I assume his charts are at the service (includes bldg load and elev?)
base 20-30 A
running 100-125
300-325 when starting

the drop at 100 A is 3-4%
when starting 8-10%

drop per calculator
2-500 Al (he has a 500 Cu also, not included here)
200'
500 A
<1.5%

 

[wyreman]

If there is one leg with worse min/max drop
on elevator start
at the elevator disco
with all other loads isolated
I'll make some precise measurements of
#min max volts clearly for each max amp draw event for each P-N leg
put this in an easy to read chart


I'll just rotate the sequence abc-cab-bca
at the elevator disco
the controller says it has phase monitoring in it

if the one weak leg moves from a => b => c at the load terminals of the disco then it must be the motor

if not, it seems hard to believe it is a bad splice coming in from pge because they doubled the service
but, there is the pesky low leg before the main when the total inrush is pretty balanced ~320a - and the xfmr is lightly loaded with a capacity of 800a ==> shouldn't bounce at all when you have a sudden 335a come in on 800
plus the [low] A Leg has the parallel feeder wires that have the 90a imbalance​

If the trouble follows the poco wires, I'll recommend to get the elevator guy to set the starting current below 200% for a few tries
see if that cures the dip

going back on Wednesday looks like now

I had a 12kv guy come out to do some maintenance at my old job
he was talking on a 12kv telephone handset
proving a wire he could lock out

I remember it well, he told me "I only deal with three wires"

 

[Electric-Light]

So did you see a noticeable difference in the amount of flicker between three bulbs and was it considerable or just barely noticeable?

Flicker do not transfer the same on camera.
Recall that you see zebra stripes in recorded video when light source contains 120 Hz flicker even though you don't see it with your own eyes.

 

[wyreman]

I saw a very pronounced dip on all three legs with the A leg is being much worse
that corresponded to the voltage that I was reading.

But my colleague thought they were pretty similar- albeit noticeable and deep saga
Duration approx 500ms
It was somewhat subjective

 

[Sahib]

What happens to the lights flickering when the standby/emergency generator, if there is one, takes over electrical supply of the building including the elevator?

 

[wyreman]

Final report

Final report

https://1drv.ms/i/s!AkuU8mYuf3eEg3DL1hY0erEJrUbS

Problem:
Three phase motor at elevator creates noticeable dimming whole apartment house every ascent

Metrics:
https://1drv.ms/i/s!AkuU8mYuf3eEgw7L1hY0erEJrUbS
As reported earlier, one leg has high amperage
390a vs 350a
https://1drv.ms/i/s!AkuU8mYuf3eEg1XL1hY0erEJrUbS
and very low instantaneous voltage
(101v vs 114v)

https://1drv.ms/i/s!AkuU8mYuf3eEg1HL1hY0erEJrUbS

https://1drv.ms/i/s!AkuU8mYuf3eEgxbL1hY0erEJrUbS



test method :

Pushed the phases ahead at the elevator disco and the trouble followed the utility line not the elevator terminals. This was one of the most useful troubleshooting tools.

Thanks to the great people on this forum for helping me take the leap of faith
https://1drv.ms/i/s!AkuU8mYuf3eEg3HL1hY0erEJrUbS

That test “Proved” to me the elevator motor was not unbalanced

Then I pushed the phase sequences ahead at the elevator shunt trip.

Same thing that trouble stayed with utility line not with the elevator terminal.

This Proved the 150’ feeder was not having higher resistance on One leg

Finally to prove the inaccessible busswork at the switchgear - I measured instantaneous voltage at two locations using a powersight 4500 data logger. Location 1 was at the utility side of the meter- affected p-n
Location 2 was at the house panel at the end of the busswork same p-n

Instantaneous Voltage at both locations was equally low
As low as 101v

So I believe I have proved my first conclusion: that poco service just not stiff enough

No fault at elevator
No fault at premise wire
No fault at busswork

Problem is : poco did double their 300’ service run and claims to have doubled the size of their tx

They have better data quality analysers (eagle 440) at 4locations:
Tx
Manhole1
Manhole2
My main switchboard
So I come to the conclusion it's a Poco problem.
I am waiting to hear results of their data logging.
Could I be I missing something?
Thanks again!

 

[wyreman]

FINAL REPORT

FINAL REPORT

POCO confirms they have weak supply coming on one leg.
Their map is mislabeled, hookups not as indicated on maps.
Each troubleshooting event on their end is cumbersome, requires street closure permits for main traffic road in town.
POCO confirms I do not need to hook up load bank to prove origin of the trouble.

thanks again!