testers

Status
Not open for further replies.
P

Paul Parry

Member
I have a similar A/C surge problem as other people that have written in. When A/C kicks on, the lights dim. A/C's are brand new 5-ton & 4-ton units. The 5-ton is located twenty feet from my 400 amp service. Wire is sized correctly and breakers at min ampacity rating on the unit. Power company says voltage is good on their end and I am loosing 1% on my end. Could this be a neutral problem, if so what kind of tester could you recommend for testing good neutral connections? What about a tester for voltage drop? Any other sugestions would be greatly appreciated. thank you!
 
J

jtester

Senior Member
Location
Las Cruces N.M.
I don't think you have an abnormal condition, or problem like a bad neutral. A 5 ton unit could draw 150+ amps when starting. The sudden increase in current causes the flicker that is seen. If the voltage suddenly drops from 122 to 120 or lower, you are going to notice it in incandescant lighting, although the voltage is within utility limits.

How long is the utility service back to the transformer, and what size transformer is serving the house?

Jim T
 
P

Paul Parry

Member
Its about 75' to the tranformer, I don't know what size it is. I will check tommorow and get back to you. thanks, Paul.
 
C

coulter

Senior Member
Question 1:
Has anyone tried to use a cap bank to reduce the inrush, as seen by the xmf and service wire, from household AC units?

The inrush is mainly inductive I would expect.

Q2:
Has anyone tried a soft start for hh AC? I don't even know if they are available for 1ph.

This AC flickering the lights seems to be a common enough problem that one would expect there to be engineered/marketed fixes.

But then again, I rarely do any single phase, so I am a bit clueless.

carl
 
brian john

brian john

Senior Member
Location
Leesburg, VA
If I have said this once, I have said it..............


The fact is flicker occurs, sensitivity has a lot to do with the amount of VD one can withstand (light wise that is).


Did a job with light flicker yesterday, I have attached the disturbances as well as a text print out of the voltage and current levels.

This house had an unusual number of incadescent light firtures 150+, and 7 HVAC units. This house had a 200 amp service that was upgraded to 600 amp, appears the utility left the 200 amp triplex in use, about 150" changed to 250 AL undereground 150, plus what appears tro be a 30 KVA pole mounted transformer (300 feet away).

Flicker is not just load, conductor lenght or transformer sizing dependent, it is also end user sensitivite. I have flicker but never really notice it, unless the wife says something. I have been to customers houses where it PLAIN WAS DRIVING the homeowner crazy and max VD recorded was 3 VAC. Others are just worried they have connection issues (a legimate concern).

NAME EDITED TO PROTECT THE INNOCENT
L1.jpg


this is just shy of 3 VAC drop, I barely noticed it the homeowner was LIVID, and ready to sue.




__________________
Brian Gaquin
Sterling, VA (Washington DC Metro)
 
Last edited:
J

jtester

Senior Member
Location
Las Cruces N.M.
A persons sensitivity is inversely proportional to his financial obligation. When the homeowner finds out how much it costs to fix it, he won't mind the flicker much at all.

Jim T
 
T

tilib

Member
homeowner will not pay more

homeowner will not pay more

From the beginning, If every item was calculated correctly, x-former size, cable between the Home & X-former , size of distribution panel, cables.
The homeowner will not pay more? But this is your trick & others like you!
 
W

wayni

Member
Brian,

I didn't see the text file - did you post it? Looking at the graph you provided though ... It looks like power factor goes downhill, and the circuit becomes inductive once the load appears. What is the load, exactly?
 
B

Ben There

Member
Location
Soonerland!
Definitely install a hard start relay & capacitor in the AC unit. This WILL shorten the duration of the starting voltage drop. I would check the service conductors including neutrals for open/loose connections, test with something like a "Beast-of-Burden" or "load-coil" type testers, you should have no more than a volt and a half, to two volt difference, raise/drop on the phase conductors, ANY movement raise/drop on the neutral is NOT good, and indicates a Bad/Open connection somewhere in the neutral. At the service mains is a good place to start, to determine if its a Utility problem, or on the metered side. I have found weak/bad connectors that looked fine on the outside using this method.
Searching out "flickering-dimming lights" problems is often tedious, time consuming work. When I was a "Trouble Shooter" at the Electric Utility I Always pulled the meter & tested the Service first. I then SMILED if it tested ok, and felt sorry for the poor SOB who had to find the source.:D
YMMV:D
 
C

coulter

Senior Member
Ben There said:
Definitely install a hard start relay & capacitor in the AC unit. ...
Click to expand...
What is a "hard start relay"?

As I said, I don't do much single phase. So a reference would help.

carl
 
brian john

brian john

Senior Member
Location
Leesburg, VA
Ben:

With the right equipment locating the source of light flicker is fairly easy.
1. Connect meter turn on the lights wait for flicker.
2. Or force motor loads on line.
3. Customer says "There, did you see that?"
4. Download meter
5. Review data.
6. Submit report
7. Usually prove to someone you can backup what you reported builder, utility or homeowner
 
B

Ben There

Member
Location
Soonerland!
coulter said:
What is a "hard start relay"?

As I said, I don't do much single phase. So a reference would help.

carl
Click to expand...

A true *Hard Start Relay* is a relay and starting capacitor designed to start/assist the A/C compressor, & is sized from the compressor nameplate data.

A universal type, ?soft-start capacitor?, is a one-size-fits-all with just a couple of leads in series with the run capacitor. Commonly used with several sizes of compressors.

Of course as you would know, :grin: 3-phase motors need No capacitors to start.
 
B

Ben There

Member
Location
Soonerland!
brian john said:
Ben:

With the right equipment locating the source of light flicker is fairly easy.
1. Connect meter turn on the lights wait for flicker.
2. Or force motor loads on line.
3. Customer says "There, did you see that?"
4. Download meter
5. Review data.
6. Submit report
7. Usually prove to someone you can backup what you reported builder, utility or homeowner
Click to expand...

I'm sure there is better equipment NOW, than I have used in the past. I have used a $5000. Drantz recorder, that now a $400. Fluke would surpass. A LOT of test equipment will tell you HAVE a problem. Finding WHERE, & FIXING it is the trick. :grin:
 
G

Greg Lescalleet

New member
Meeting IEC 6060101 specs

Meeting IEC 6060101 specs

Does anyone out know of tester that will test the conductor to conductor leakage on three prong plugs and cords? Looking for a simily meter that can be pluged into a non energizied power cord to test for leakage. The spec's ask for 0.2 ohms and 500 micro A leakage current. I understand the reason for the test to make sure any of the conductors insulators have not been damaged due to well any kind of external force that may not be visible. Or internal damage as well. Any help in this area would be appreciated. thanks
 
Status
Not open for further replies.
Top