Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Motor slowing when electric dryer comes on

The utility co. took down their recording voltmeter. It was on the
weatherhead, on my roof where the power line is attached.

I talked to an engineer at the utility co. today, and he said
everything is fine with my voltage. He said it's between 120 and 124
volts usually, he saw one time it went down to 115 volts.

The only thing he noticed was that the load is somewhat unbalanced,
like 25 amps on one leg and 10 amps on the other, usually.

Could an unbalanced load cause voltage fluctuations?

One day when I was doing my laundry and the heat pump may have been
working hard, he said the load went up to 55 amps. I don't know if
this could cause flaky voltage inside my house, it's 100-amp service.

I might borrow or buy a voltmeter, and see whether voltage at the
outlet correlates with the drastic fluctuations in airflow that I've
noticed.

I doubt it's the fault of the motor volume control, because the
airflow goes up rather predictably at night.

And like I said, when I use the electric dryer, the airflow
predictably goes down, sometimes a lot.

Maybe there's something other than just voltage that might be
affecting the turbine speed. Some other power quality issue, perhaps.

Laura


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Default Motor slowing when electric dryer comes on

On 6/13/2012 7:25 PM, Laurav wrote:
The utility co. took down their recording voltmeter. It was on the
weatherhead, on my roof where the power line is attached.

I talked to an engineer at the utility co. today, and he said
everything is fine with my voltage. He said it's between 120 and 124
volts usually, he saw one time it went down to 115 volts.

The only thing he noticed was that the load is somewhat unbalanced,
like 25 amps on one leg and 10 amps on the other, usually.

Could an unbalanced load cause voltage fluctuations?

One day when I was doing my laundry and the heat pump may have been
working hard, he said the load went up to 55 amps. I don't know if
this could cause flaky voltage inside my house, it's 100-amp service.

I might borrow or buy a voltmeter, and see whether voltage at the
outlet correlates with the drastic fluctuations in airflow that I've
noticed.

I doubt it's the fault of the motor volume control, because the
airflow goes up rather predictably at night.

And like I said, when I use the electric dryer, the airflow
predictably goes down, sometimes a lot.

Maybe there's something other than just voltage that might be
affecting the turbine speed. Some other power quality issue, perhaps.

Laura


Any chance you share the power transformer with other houses? If so,
their use will have a noticeable effect on your voltage with only a 100
amp service.

Paul
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Default Motor slowing when electric dryer comes on

On Jun 13, 11:03*pm, Paul Drahn wrote:

Any chance you share the power transformer with other houses? If so,
their use will have a noticeable effect on your voltage with only a 100
amp service.


There are about 6 houses on the same transformer. So if I upgraded
the service, that would help?

Laura

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Default Motor slowing when electric dryer comes on

Laurav wrote:
On Jun 13, 11:03 pm, Paul Drahn wrote:

Any chance you share the power transformer with other houses? If so,
their use will have a noticeable effect on your voltage with only a
100 amp service.


There are about 6 houses on the same transformer. So if I upgraded
the service, that would help?

Laura


Before you go to the trouble and expense of upgrading your service, you need
to focus more on what and where the problem is. Your original post isn't
clear about where the slowing motor is... is it in the dryer or a different
appliance?
Usually, a dryer is on a completely independent circuit, so it would be a
good idea to inspect the circuit breakers or fuse(s) associated with the
problematic appliances. Measure the voltages at the breakers and/or fuses
with and without the dryer running. That should tell the tale.

Be sure you know how to use the voltmeter and be very careful when making
the measurements, Ask a knowledgable friend or an electrician to help if
you're unsure of what you're doing. The voltages and currents available
inside a distribution panel and wall outlets are LETHAL.

--
Dave M
A woman has the last word in any argument. Anything a man says after
that is the beginning of a new argument.


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Default Motor slowing when electric dryer comes on

On Jun 14, 6:59*am, "Dave M" wrote:

Before you go to the trouble and expense of upgrading your service, you need
to focus more on what and where the problem is. *Your original post isn't
clear about where the slowing motor is... is it in the dryer or a different
appliance?


This is actually a followup to an old thread from April/May. It's an
air turbine, it consumes about 2 amps. It's very voltage-sensitive,
once the electrician measured voltage at the outlet when I turned my
electric dryer on, the voltage went down by 2 volts, and the speed
went down noticeably. I just got it put on its own circuit, so I'm
sure the circuit breaker is OK.

So I was thinking of measuring the voltage at the outlet. Is this
reasonably safe?

Could the voltage at the outlet be varying more than the voltage at
the weatherhead? The recording voltmeter was recording voltage at
both sides. Could uneven load cause the voltage at the outlet to
change more than voltage at the weatherhead?

Laura


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Default Motor slowing when electric dryer comes on

On 6/13/2012 8:38 PM, Laurav wrote:
On Jun 13, 11:03 pm, Paul wrote:

Any chance you share the power transformer with other houses? If so,
their use will have a noticeable effect on your voltage with only a 100
amp service.


There are about 6 houses on the same transformer. So if I upgraded
the service, that would help?

Laura

I had to do that last summer as part of a new heat pump with electric
heat backup. Cost $1500 up front for the power company to upgrade the
transformer. There are a total of 3 houses on my transformer.

Where do you live? I am really surprised that the power company would
put 6 houses on the same transformer. Houses must be located pretty
close together.

Paul
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Default Motor slowing when electric dryer comes on


Where do you live? I am really surprised that the power company would
put 6 houses on the same transformer. Houses must be located pretty
close together.


Maybe that's the problem. I get the impression that many of the
changes in speed in the air turbine are being caused by other people's
usage. I live in upstate NY.

So is it possible for an unbalanced load to cause the voltage at an
outlet to be different from what the power co. measures at the
weatherhead?
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Default Motor slowing when electric dryer comes on

On 06/14/2012 08:56 AM, Laurav wrote:
On Jun 14, 6:59 am, "Dave wrote:

Before you go to the trouble and expense of upgrading your service, you need
to focus more on what and where the problem is. Your original post isn't
clear about where the slowing motor is... is it in the dryer or a different
appliance?


This is actually a followup to an old thread from April/May. It's an
air turbine, it consumes about 2 amps. It's very voltage-sensitive,
once the electrician measured voltage at the outlet when I turned my
electric dryer on, the voltage went down by 2 volts, and the speed
went down noticeably. I just got it put on its own circuit, so I'm
sure the circuit breaker is OK.

So I was thinking of measuring the voltage at the outlet. Is this
reasonably safe?

Could the voltage at the outlet be varying more than the voltage at
the weatherhead? The recording voltmeter was recording voltage at
both sides. Could uneven load cause the voltage at the outlet to
change more than voltage at the weatherhead?

Laura


Do any of your lights become _brighter_ when the dryer turns on? If so,
you may have a problem with the neutral.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net
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Default Motor slowing when electric dryer comes on

On Jun 14, 2:26*pm, Phil Hobbs
wrote:
Could uneven load cause the voltage at the outlet to
change more than voltage at the weatherhead?


Laura


Do any of your lights become _brighter_ when the dryer turns on? *If so,
you may have a problem with the neutral.


Could a problem with the neutral cause voltage fluctuations at an
outlet, that don't appear on the weatherhead?
I have fluorescent lights. Occasionally they flicker off. This
happened on May 27, and it didn't seem to show up on the utility co's
record of my voltage.

If I have a problem with the neutral, would it be inside my house, or
a utility co. problem?

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot nethttp://electrooptical.net


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Default Motor slowing when electric dryer comes on

When I had incandescent lights, they did flicker sometimes. Not
terribly often, though.
Is it worth it, to get a voltmeter to see how much the voltage is
changing at the outlet where the air turbine is plugged in? Can that
voltage be different from what the utility co. measures?


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Default Motor slowing when electric dryer comes on

Laurav wrote:
On Jun 14, 6:59 am, "Dave M" wrote:

Before you go to the trouble and expense of upgrading your service,
you need to focus more on what and where the problem is. Your
original post isn't clear about where the slowing motor is... is it
in the dryer or a different appliance?


This is actually a followup to an old thread from April/May. It's an
air turbine, it consumes about 2 amps. It's very voltage-sensitive,
once the electrician measured voltage at the outlet when I turned my
electric dryer on, the voltage went down by 2 volts, and the speed
went down noticeably. I just got it put on its own circuit, so I'm
sure the circuit breaker is OK.

So I was thinking of measuring the voltage at the outlet. Is this
reasonably safe?

Could the voltage at the outlet be varying more than the voltage at
the weatherhead? The recording voltmeter was recording voltage at
both sides. Could uneven load cause the voltage at the outlet to
change more than voltage at the weatherhead?

Laura


Yes, the voltage at an outlet can vary more than at the weatherhead because
there are seveeral wire connections in the line before getting to the
outlet.
First, there's the breaker panel where the breakers tap off the main line
from the weatherhead.
Then, there's the wire that connects to the load side of the breaker.
Then, there are one or more connections that split off to multiple outlets.
Any of these connection points could be causing a voltage drop if any of the
wiring connections are loose or if the wire is too small for the service.
In either case, there exists the possibly of overheating and fire.

Having said all that, your statement that an electrician measured a 2-volt
voltage drop at the outlet when the dryer turned on leads me to another
thought. What gauge wire is used to supply the outlets? Normally, a 15-amp
circuit should be wired with 14-gauge copper wire or 12-gauge aluminum.
Is it copper wire or aluminum? If it's aluminum, you really should have
someone check all of the outlets in your house to make sure the screws are
all still tight.
I used to live in a house in Florida (built in 1976), that was wired with
aluminum wire, but the ends of the wire was stuffed into the quick-connect
hole in the receptacle. I had trouble almost from the day I moved into the
house with arcing, sparking, and smoke coming from the outlets. I had to
pull out every receptacle in my house and put the wires under the screws, as
they should be.
It could be that the turbine motor is just very sensitive to voltage change,
and nothing short of replacing the motor or the entire turbine unit will fix
it. Did the electrician tell you what the actual voltages at the turbine
were, with the dryer running and not running?

--
Dave M
A woman has the last word in any argument. Anything a man says after
that is the beginning of a new argument.


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Default Motor slowing when electric dryer comes on

Laurav wrote:
When I had incandescent lights, they did flicker sometimes. Not
terribly often, though.
Is it worth it, to get a voltmeter to see how much the voltage is
changing at the outlet where the air turbine is plugged in? Can that
voltage be different from what the utility co. measures?


Almost any digital voltmeter that you buy today (even the cheap ones from
the likes of Harbor Freight, such as the one here
http://www.harborfreight.com/7-funct...ter-98025.html) are plenty
accurate enough for you to get useful info about your problem. Just be
careful not to touch any exposed metal (probe tips) when measuring. While
you're buying a voltmeter, buy a receptacle wiring tester, such as this one
(http://www.harborfreight.com/electri...er-32906.html). That
will tell you if the receptacles are wired correctly.
If you don't have a Harbor Freight store near you, you can also get these at
Walmart, Sears, Home Depot, Lowes, etc.

--
Dave M
A woman has the last word in any argument. Anything a man says after that is
the beginning of a new argument.


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Default Motor slowing when electric dryer comes on

On 06/14/2012 02:31 PM, Laurav wrote:
On Jun 14, 2:26 pm, Phil Hobbs
wrote:
Could uneven load cause the voltage at the outlet to
change more than voltage at the weatherhead?


Laura


Do any of your lights become _brighter_ when the dryer turns on? If so,
you may have a problem with the neutral.


Could a problem with the neutral cause voltage fluctuations at an
outlet, that don't appear on the weatherhead?
I have fluorescent lights. Occasionally they flicker off. This
happened on May 27, and it didn't seem to show up on the utility co's
record of my voltage.

If I have a problem with the neutral, would it be inside my house, or
a utility co. problem?


I'm not an electrician, but I believe that most houses in the US have
two-phase service, and that the neutral is bonded to the ground rod near
the service entrance. Voltage drops in the neutral make one side go
down in voltage and one side go up.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net
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Default Motor slowing when electric dryer comes on

On Jun 14, 2:26*pm, Phil Hobbs
wrote:
Do any of your lights become _brighter_ when the dryer turns on? *If so,
you may have a problem with the neutral.


The voltage at the turbine outlet goes up by about 1 volt when the 1
kW microwave goes on. They're on opposite sides of the service. Is
this a significant amount?
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Default Motor slowing when electric dryer comes on

Phil Hobbs wrote:

(...)

I'm not an electrician, but I believe that most houses in the US have
two-phase service,


Nup. Single phase, center tapped.

http://en.wikipedia.org/wiki/Split-phase_electric_power

and that the neutral is bonded to the ground rod near
the service entrance. Voltage drops in the neutral make one side go down
in voltage and one side go up.


Yup.

--Winston



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Default Motor slowing when electric dryer comes on

On Thu, 14 Jun 2012 16:01:03 -0400, Phil Hobbs
wrote:

On 06/14/2012 02:31 PM, Laurav wrote:
On Jun 14, 2:26 pm, Phil Hobbs
wrote:
Could uneven load cause the voltage at the outlet to
change more than voltage at the weatherhead?

Laura

Do any of your lights become _brighter_ when the dryer turns on? If so,
you may have a problem with the neutral.


Could a problem with the neutral cause voltage fluctuations at an
outlet, that don't appear on the weatherhead?
I have fluorescent lights. Occasionally they flicker off. This
happened on May 27, and it didn't seem to show up on the utility co's
record of my voltage.

If I have a problem with the neutral, would it be inside my house, or
a utility co. problem?


I'm not an electrician, but I believe that most houses in the US have
two-phase service, and that the neutral is bonded to the ground rod near
the service entrance. Voltage drops in the neutral make one side go
down in voltage and one side go up.

Cheers

Phil Hobbs


That is still single phase service.

?-)
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Default Motor slowing when electric dryer comes on

On Thu, 14 Jun 2012 17:53:01 -0700 (PDT), Laurav
wrote:

On Jun 14, 2:26*pm, Phil Hobbs
wrote:
Do any of your lights become _brighter_ when the dryer turns on? *If so,
you may have a problem with the neutral.


The voltage at the turbine outlet goes up by about 1 volt when the 1
kW microwave goes on. They're on opposite sides of the service. Is
this a significant amount?


It does indicate a problem developing.

?-)
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On Thu, 14 Jun 2012 10:22:10 -0700 (PDT), Laurav
wrote:


Where do you live? I am really surprised that the power company would
put 6 houses on the same transformer. Houses must be located pretty
close together.


Maybe that's the problem. I get the impression that many of the
changes in speed in the air turbine are being caused by other people's
usage. I live in upstate NY.

So is it possible for an unbalanced load to cause the voltage at an
outlet to be different from what the power co. measures at the
weatherhead?


Only to the extent that the unbalance is internal to your house. Which
may explain all of it or not, seriously have your neutral wiring checked
as well.

?-)
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Default Motor slowing when electric dryer comes on

On Jun 17, 5:49*pm, josephkk wrote:
On Thu, 14 Jun 2012 16:01:03 -0400, Phil Hobbs



wrote:
On 06/14/2012 02:31 PM, Laurav wrote:
On Jun 14, 2:26 pm, Phil Hobbs
*wrote:
Could uneven load cause the voltage at the outlet to
change more than voltage at the weatherhead?


Laura


Do any of your lights become _brighter_ when the dryer turns on? *If so,
you may have a problem with the neutral.


Could a problem with the neutral cause voltage fluctuations at an
outlet, that don't appear on the weatherhead?
I have fluorescent lights. *Occasionally they flicker off. *This
happened on May 27, and it didn't seem to show up on the utility co's
record of my voltage.


If I have a problem with the neutral, would it be inside my house, or
a utility co. problem?


I'm not an electrician, but I believe that most houses in the US have
two-phase service, and that the neutral is bonded to the ground rod near
the service entrance. *Voltage drops in the neutral make one side go
down in voltage and one side *go up.




That is still single phase service.


As Winston said. Here's how Phil H. is correct:

Household electricity 101: Residences get single phase 240, split into
two 120 leads and neutral. Stoves and dryers get the full 240, other
appliances get 120 VAC. If the load on each 120 VAC lead is the same,
no current will flow on the neutral.

If, the loads on the two leads are different, and current flows on the
neutral, AND the neutral is resistive, then the voltage on the more
heavily loaded leg will be less by the amount of the voltage drop on
the neutral. Which means the voltage on the more lightly loaded leg
will be more, by the amount of the voltage drop on the neutral.
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