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

[Bugman1400]

I don't think its a loose connection....I think its a weak source but, one could look like the other. If you do try the load test make sure your data loggers are armed. Also, try and get the short circuit availability from the POCO at the service connection. Please post your data logger results and any Flir captures.

 

[Electric-Light]

My niche is lighting.

Human sensitivity to flicker is very high. It's not just magnitude, but also the frequency and we're most sensitive around 8 Hz. A welder set to wrong duty cycle setting and load down the line at just the right frequency to cause fluctuation at sensitivity peak is enough to cause complaints.

Also, not all 120-277v electronic ballasts respond at the same speed. Some will flicker at sharp dip. Some will not let you know about a compressor starting on the same branch.

A data logger is not really appropriate for testing this. You'd want a power QUALITY analyzer which is specifically designed to look for thing like this.

 

[gar]

170213-1710 EST

wyreman:

It is my opinion, from a remote point meaning I can't do the probing, that you have a very simple problem to initially determine if the problem is the power company or on your side of the meter.

A min-max voltage test before and after the meter is all that is needed. You already have the test load, your elevator. The test can be performed without any inconvenience to the tenants.

I believe you have a wye source. Connect a Fluke 27 meter between line and neutral. Select AC, then push min-max, operate the elevator, readout min-and max. Is it excessive? If so, then power company is the likely problem. If power company appears OK, then repeat on the other two phases.

If power company looks OK, then repeat at any other places you like.

An experiment at my son's shop. Source is a 240 V three phase open delta. Test load a 20 HP motor induction motor with a moderate inertia load, a wide belt sander. With CNC machines doing whatever they wanted a short time min-max was 122.1 to 121.5.

Two different tests with 20 HP motor were:
121.7 to 115.2 and 122.0 to 112.5 .
Maximum current measurements were 195 and 235 A.

The total transformer ca[ability is about 150 to 175 kVA.
One transformer is about 100 kVA.

Three is about 300 ft of 00 copper, and about another 50 ft of heavier copper to the transformers.

.

 

[Sahib]

I don't think its a loose connection....I think its a weak source but, one could look like the other. If you do try the load test make sure your data loggers are armed. Also, try and get the short circuit availability from the POCO at the service connection. Please post your data logger results and any Flir captures.

A weak source may be easily ascertained by measuring fault level at OP service meter location. It is one thing to calculate fault level, a laborious procedure. But,it is easy to measure the same. From the data of voltage drop for a given load, the fault level may be found out.

 

[Bugman1400]

My niche is lighting.

Human sensitivity to flicker is very high. It's not just magnitude, but also the frequency and we're most sensitive around 8 Hz. A welder set to wrong duty cycle setting and load down the line at just the right frequency to cause fluctuation at sensitivity peak is enough to cause complaints.

Also, not all 120-277v electronic ballasts respond at the same speed. Some will flicker at sharp dip. Some will not let you know about a compressor starting on the same branch.

A data logger is not really appropriate for testing this. You'd want a power QUALITY analyzer which is specifically designed to look for thing like this.

A data logger to me is the same as a power quality meter (ie Dranetz or whatever PQ meter you prefer). If a data logger to you means something else then, I do not recommend that.

 

[wyreman]

loose nut

loose nut

even after they replaced /upgraded the xfmrs
and pulled in the parrallel set of wires
- the VD is getting worse

I measure this before the meter 187v from nominal 208v
California PUC mandates 197v

POCO doesnt want to do more as he believes he has fullfilled any reasonable calc.

I find the dip only on one shared leg ie
a-b good enough
a-c weak
b-c very weak

and infer it must be a loose nut so to speak on the c post
But hard to argue when he also pulled new wire- that the original copper had a bad splice in one of the manholes

Very frustrating, but he is not in compliance with the PUC mandate of 197v so ...

the only other thing is that on leg runs with - that is the one with the low voltage
againlends credence to the idea of loose nuts

 

[iwire]

A data logger to me is the same as a power quality meter (ie Dranetz or whatever PQ meter you prefer). If a data logger to you means something else then, I do not recommend that.

We have both PQ meters (PX5 power explorer) and much more basic data loggers that just do basic current, voltage power no PQ functions.

 

[mbrooke]

Question, are the smaller feeders coming of the main for a fire pump? Normally I would assume parallel but I'm confused.

 

[gar]

170222-1350 EST

wyreman:

If your voltage measurements are really before the meter, the power company is responsible for anything up to and including the meter, and your load current at the time of the voltage measurement is less than the load current that your power company is expected to supply, then the power company is responsible to solve the problem and I would go to the public service commission and complain since the power company is not willing to solve the problem.

I would like to see the line to neutral voltages, and their associated line currents when the elevator starts. Also is there a difference in the elevator starting and running current? If so, then we should know what are the associated current and voltage measurements for both starting and running, and the duration of the starting current.

If starting only occurs for a part of a second, then a typical DVM like a Fluke 27 won't provide a very good measurement because of its response time. However, the Fluke 27 in min-max has a fractional part of a second response, but not milliseconds.

It would be nice to have meter response time of 8.3 millisecond and synchronized to line voltage zero crossings, but that would be a specialized unit. I don't remember the response time for the 27 in min-max, but it is probably somewhat less than 0.1 seconds or 6 cycles. In standard mode it is about 2 to 3 seconds.

.

 

[Jraef]

Question, are the smaller feeders coming of the main for a fire pump? Normally I would assume parallel but I'm confused.

Most likely, the elevator starter is wired as "inside the delta", something that industry does quite a lot. The motor is configured for Wye-Delta starting, but basically just to get all 6 ends of the windings brought out to the controller. Then the soft starter is wired in SERIES with each winding and is thereby only required to carry 58% of the motor current, so the soft starter can be cheaper. When they do that, one set of conductors can also be smaller than the other. It's a risky thing to do just to save a few bucks, but that industry uses so many soft starters that it pays off on a grander scale for the OEMs.

 

[wyreman]

Question, are the smaller feeders coming of the main for a fire pump? Normally I would assume parallel but I'm confused.

this is the pull box before the meter.

the calcs call for parallel big conductors [dont remember... 750mcms?]
=> two pipes were supplied
original crew only pulled one set

i complained about the voltage and they [first refused and then] pulled new conductors
And a new upsized xfmr bank!!!!

the set in the photo is the original wire pull, the pipe on the left are the new , smaller wires

now that you mention it, i remember that , in parallel conductors, they say
if the resistance is mismatched because of size or length, most all the current will flow on the bigger/shorter wire.
So maybe the smaller wires are doing absolutely nothing! Well that would explain a lot hmmm...
got to go back, again
make more detailed measurements

L-N [3X]
amp flow on individual conductors in the parallel pairs

the powersight 3000's quickest sample rate is 1 second - it really didn't capture the voltage changes that well
i'll check to see which of my meters has the fastest sampling rate, but those klein clamps did just fine- just like a regular multimeter
went as low as 187v instantaneous with the building very lightly loaded

 

[Ingenieur]

Let's say
load 100 A
large existing conductor is 0.1 Ohm, Vdrop 10
New small one is 0.2 Ohm

Req = 0.067 Ohm, so lower, Vdrop 6.7 V
Current
large 67 A, Vdrop 6.7 V
small 33 A, Vdrop 6.7 V
so lower, both 6.7 vs single large 10

 

[wyreman]

Let's say
load 100 A
large existing conductor is 0.1 Ohm, Vdrop 10
New small one is 0.2 Ohm

Req = 0.067 Ohm, so lower, Vdrop 6.7 V
Current
large 67 A, Vdrop 6.7 V
small 33 A, Vdrop 6.7 V
so lower, both 6.7 vs single large 10

sorry, :ashamed::dunce:
does that mean that two conductors are better than one, even tho one is big and one is small?
:ashamed::slaphead:

 

[mbrooke]

this is the pull box before the meter.

the calcs call for parallel big conductors [dont remember... 750mcms?]
=> two pipes were supplied
original crew only pulled one set

i complained about the voltage and they [first refused and then] pulled new conductors
And a new upsized xfmr bank!!!!

the set in the photo is the original wire pull, the pipe on the left are the new , smaller wires

now that you mention it, i remember that , in parallel conductors, they say
if the resistance is mismatched because of size or length, most all the current will flow on the bigger/shorter wire.
So maybe the smaller wires are doing absolutely nothing! Well that would explain a lot hmmm...
got to go back, again
make more detailed measurements

L-N [3X]
amp flow on individual conductors in the parallel pairs

the powersight 3000's quickest sample rate is 1 second - it really didn't capture the voltage changes that well
i'll check to see which of my meters has the fastest sampling rate, but those klein clamps did just fine- just like a regular multimeter
went as low as 187v instantaneous with the building very lightly loaded

POCO pulled the new wires or your crew? Being honest I have never seen such and per the NEC it would be incorrect. The current will not divide evenly, and its possible that one set (the smaller wires) could overheat if the load is high enough. Code requires that all conductors in parallel be the same size and length. If you are getting voltage that low at the service, then it would be a POCO issue.

 

[mbrooke]

Let's say
load 100 A
large existing conductor is 0.1 Ohm, Vdrop 10
New small one is 0.2 Ohm

Req = 0.067 Ohm, so lower, Vdrop 6.7 V
Current
large 67 A, Vdrop 6.7 V
small 33 A, Vdrop 6.7 V
so lower, both 6.7 vs single large 10

If the smaller wire ends up being shorter, won't it over heat (carry more then listed current in 310.15 B 16)?

 

[wyreman]

POCO pulled the new wires or your crew? Being honest I have never seen such and per the NEC it would be incorrect. The current will not divide evenly, and its possible that one set (the smaller wires) could overheat if the load is high enough. Code requires that all conductors in parallel be the same size and length. If you are getting voltage that low at the service, then it would be a POCO issue.

POCO pulled it.

I dont want to have to go to the public utilities commission :/

 

[mbrooke]

POCO pulled it.

I dont want to have to go to the public utilities commission :/

Since they do not follow the NEC it might technically be ok, but Id be curious whats behind that low voltage. How far away if the transformer? Its possible all thats needed is adjustment of the taps (if present).

 

[Electric-Light]

Ingineur, I Googled the controller. It's like a three phase ceiling fan speed controller with a computer controlled slider. Upon reaching full speed, it gives "ready" signal at which point the elevator controller opens ascend valve.

Have you done the three light bulb test?
You connect a filament light bulb (28 or 40W) L-N on each phase. Three of them lined up, side by side simultaneously. This is still the best way to prove flicker complaint unless you have a THREE PHASE instrument with flicker test capability. If this doesn't pass, you have to see if it's line or load side
Light bulbs are in sync and you are watching to see if one bulb flickers significantly more than the other two.
An array of three single phase meters are not in sync and digit readouts are not appropriate for this kind of test on their own

If you have a 4 3/4 digit meter like 289, you could apply a 20A heater L-N on each phase one at a time and compare loaded vs unloaded and expand and it would be a good way of narrowing down suspected loose phase connection. 2.22v drop at 20A = 22.2v at 200A. A loose connection likely won't coincide to the same drop on all three phases. The test load is selected to balance between getting good enough readability and ease of handling. 2A on a 200A circuit likely won't produce strong enough signal.

If all three phases behave the same with resistance test, then I would suspect the load. The motor looks quite classic. Have you done AC resistance test on all the windings? You apply a few volts at 60 Hz on each winding and test the amps and verify that no one winding stands out.

 

[wyreman]

awesome!

I can do that... and I will!
but the bottom line is that there is no way the problem is on my side because I measure these dips before the meter.
And not only that... but for some reason I saw, but it didn't register, that the new wire pull has => smaller conductors!!!
Something is wrong w this picture and it is all on their side of the frame.

What the remedy was explained by their estimator was

In review. We’ve doubled the size of the TX’s from 3-50KVA to 3-100KVA 120/208V SS Round TX’s. In total quadrupled the secondary size from the smallest section 1-1/0Cu to a continuous 500Cu run, including a #5 Box to accommodate that. Of course doubling the service run as well from 1-1000Al QPX to include 1-500Cu QPX. Loosely speaking we’ve doubled the size of everything. The only solution that remains is adding a TX right outside the building which at this point is likely causing its own voltage issue and may not solve the problem. I’ll check in with both of you after I get the monitors back and review with Power Quality Engineers. I’d expect to see a visible difference in drop at this point and based on Laynes observations have me looking right back at the MSP. MAIN SERVICE PANEL​

and the lastest word was

We have received the results back form the monitor at your main switch, the results mirror those found at the distribution point. We can come to no other conclusion then your elevator is causing your issue. I’ve attached a link of the Tariff on file with the CPUC in regard to this, please review Section F.4.a and F.4.d. It’s our recommendation based on your loading results that you reevaluate your soft starter settings. At this point we can find no other remedy to the PG&E secondary electric distribution system that will solve your issue. http://www.pge.com/tariffs/tm2/pdf/ELEC_RULES_2.pdf​

seems like it is all just one loose nut

 

[wyreman]

Ingineur, I Googled the controller. It's like a three phase ceiling fan speed controller with a computer controlled slider. Upon reaching full speed, it gives "ready" signal at which point the elevator controller opens ascend valve.

Have you done the three light bulb test?
You connect a filament light bulb (28 or 40W) L-N on each phase. Three of them lined up, side by side simultaneously. This is still the best way to prove flicker complaint unless you have a THREE PHASE instrument with flicker test capability. If this doesn't pass, you have to see if it's line or load side
Light bulbs are in sync and you are watching to see if one bulb flickers significantly more than the other two.
An array of three single phase meters are not in sync and digit readouts are not appropriate for this kind of test on their own

If you have a 4 3/4 digit meter like 289, you could apply a 20A heater L-N on each phase one at a time and compare loaded vs unloaded and expand and it would be a good way of narrowing down suspected loose phase connection. 2.22v drop at 20A = 22.2v at 200A. A loose connection likely won't coincide to the same drop on all three phases. The test load is selected to balance between getting good enough readability and ease of handling. 2A on a 200A circuit likely won't produce strong enough signal.

If all three phases behave the same with resistance test, then I would suspect the load. The motor looks quite classic. Have you done AC resistance test on all the windings? You apply a few volts at 60 Hz on each winding and test the amps and verify that no one winding stands out.

No I didn't bother as each time the problem was found before the meter.
But that's a most excellent idea!
I'll test for same same same open at the motor terminals with an ohm meter