Maestro Dimmer Giving Me Fits!

ELA

Senior Member
Thanks for your test data Little Bill,
I was most interested in the 80 ma when the loads are off to see that it was something somewhat significant as compared to Microamps which would make it more susceptible to interference.
Where are the voltage readings taken? It would also be interesting to know how much voltage is dropped across the transmitter itself when no loads are on.

These readings may be of some use to you, as a baseline to compare against, if you then take the same readings at the customer location.

Based on the 80ma reading I would no longer suggest adding an additional "dummy" load at the canopy.

Do you have a neutral in the box where the transmitter is? If so then the capacitor idea in that box might be a good first attempt.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Thanks for your test data Little Bill,
I was most interested in the 80 ma when the loads are off to see that it was something somewhat significant as compared to Microamps which would make it more susceptible to interference.
Where are the voltage readings taken? It would also be interesting to know how much voltage is dropped across the transmitter itself when no loads are on.

These readings may be of some use to you, as a baseline to compare against, if you then take the same readings at the customer location.

Based on the 80ma reading I would no longer suggest adding an additional "dummy" load at the canopy.

Do you have a neutral in the box where the transmitter is? If so then the capacitor idea in that box might be a good first attempt.

The readings were taken at the canopy module/receiver. I just had this test set up across my work bench. I had a clamp on amp meter and a DMM, set on LoZ, connected.

There is a neutral in the box at the customer's house. Luckily his is a fairly new house and power is brought into the switch instead of to the light.

I suppose I could or should have just left the wall control hanging out of the box at my fan location and took readings from the wall control. But I was trying to get the readings you were interested in, which was at the receiver/module.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
140510-1558 EDT

Little Bill:

I have found incandescent bulbs to be fairly close to rated wattage at rate voltage.

A 100 W reads 122.4 V 0.83 A 101 W calculated power 101.6 W.
A 060 W reads 122.7 V 0.49 A 061 W calculated power 060.1 W.

With a Lutron three wire dimmer I read 58 W on the 60 W bulb.

Your calculated power values are low. This implies the dimmer function is not turning on at 0 deg, but some phase shift later at maximum on, and I would expect that.

Back in one of the earlier posts I suggested putting a 0.1 to 1.0 ufd ceramic capacitor in parallel with the input side of the Lutron control. At 60 Hz this is about 26,000 ohms, and lower as frequency increases. Use a 1000 V rating. The capacitor will dissipate very little power. A 1 ufd will have 1/10 the impedance of the 0.1 at any specific frequency that is moderately below self resonance of the capacitor. 1 ufd gets bigger and more expensive.

If a low source impedance is needed at higher frequencies, then a simple capacitor may solve the problem.

Are you able to get the control back into its malfunction state at your home?

If possible it is important to try to find the source that causes the malfunction. Since it remained in the bad state while you transported the control from one place to another it implies corruption of some memory location for some parameter in the control.

.

I didn't get the control to malfunction here. But anytime you take it loose as I did and put it with a different receiver/canopy module, you have to reactivate it. This is accomplished via the little (FASS) service switch. You pull it out and leave it for 10 secs. then push it back in. Both the top and bottom section LEDs will scroll until the two parts sync, then the unit is ready.

Reactivating is not the same as a factory or hard reset.
 

GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
Bill, I've been following this thread because I'm a big fan of the Lutron Maestro fan/light control when 2 switched lines are not available; it's faster and less expensive than snaking 12-3 or 14-3. BUT ... your MIR-LFQMT- is designed for multiple control points as well. I've never used it.

It sounds to me that you have a single control point. Their single control point system is the MA-LHQHW-. Is there any possibility that lack of a 2nd (I think up to 4 are supported) could have an impact on your situation?
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Bill, I've been following this thread because I'm a big fan of the Lutron Maestro fan/light control when 2 switched lines are not available; it's faster and less expensive than snaking 12-3 or 14-3. BUT ... your MIR-LFQMT- is designed for multiple control points as well. I've never used it.

It sounds to me that you have a single control point. Their single control point system is the MA-LHQHW-. Is there any possibility that lack of a 2nd (I think up to 4 are supported) could have an impact on your situation?
I don't think so since he has the same unit in his bedroom and only one control point.
Also, I have two of these at my house, each with a single control point.

Edit: Also, given the fact that the instruction/spec sheet shows either one location or multi-location connections means it's fine for single location use.
 
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Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Gar, (or anyone)

Do you know where I can get a capacitor like you mentioned in the quote below. I looked on-line and either I don't find any place that sells just one or small quanity or I don't find the 1000V rated one.
About the only local place we have is Radio Shack and I haven't looked there. I hate going there, the workers are clueless!:happyyes:

Back in one of the earlier posts I suggested putting a 0.1 to 1.0 ufd ceramic capacitor in parallel with the input side of the Lutron control. At 60 Hz this is about 26,000 ohms, and lower as frequency increases. Use a 1000 V rating. The capacitor will dissipate very little power. A 1 ufd will have 1/10 the impedance of the 0.1 at any specific frequency that is moderately below self resonance of the capacitor. 1 ufd gets bigger and more expensive.
 

gar

Senior Member
140513-0724 EDT

Little Bill:

The ceramic I found were too expensive for an initial experiment.

Try polyester film.

Mouser:
Page 1019 in my catalog.
CD DME6P1K-F 0.1 ufd 250 VAC
CD DME6W1K-F 1.0 ufd 250 VAC

.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
140513-0724 EDT

Little Bill:

The ceramic I found were too expensive for an initial experiment.

Try polyester film.

Mouser:
Page 1019 in my catalog.
CD DME6P1K-F 0.1 ufd 250 VAC
CD DME6W1K-F 1.0 ufd 250 VAC

.
Thanks, I didn't know anyone would sell such a small quantity. Would I need to solder it in with the wires or would a wire nut do?
 

gar

Senior Member
140513-2111 EDT

Little Bill:

For experimental purposes I would use some Belden 8521 #16 stranded 1000 V hookup wire to make pigtails from the capacitor. Twist the 8521 to the capacitor lead and solder. Cover the solder connection with heatshrink. Then wrap leads and capacitor together with Scotch 33. If it solves the problem, then use appropriate wire for the application and encapsulate in an epoxy module.

Will it be UL listed? No. Solve that problem some way.

.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Update & A Good One at That

Update & A Good One at That

Ok I finally got to go back to the customer's house. He had other work for me, so after I finished that I went back to the dimmer/fan control issue.

I told him I wanted to try something even though it meant taking the fan down again for the umpteenth time!:( He said if what I was going to try didn't work, I could just leave the unit in place and he would just turn on the other lights so that the unit would work.

First I decided to go through the living room where the dimmer/control is located and unplug everything in the room. Also did the same to the kitchen since they share the lighting circuit. Although the affected circuit is only lights with the receps on a different circuit, I wanted to rule out anything close that might be causing the issue.

With everything unplugged I tried the unit again, but to no avail.....same issue.

So I tried Gar's suggestion of putting a capacitor in parallel with the wall control. I had two caps, a 0.1uf and a 1.0uf. I tried the 0.1 first as it's smaller and would take up less room in the box.

Wa-la! The dimmer/control worked just like it should!:happyyes: Also, the same as having the other lights on.

I know another load in parallel made the unit work. Now can someone tell me what putting the capacitor parallel with the control did?
Was it mimicking a load?
It doesn't really matter as long as it worked, but I would like to know exactly how this worked.

Also, to add, I found out the customer has been having trouble with his electric gates at his driveway. They also use a remote similar to a garage door opener. Could this have any bearing on the problem with the dimmer/control in the house?

I would like to thank everyone that has offered help with this. I don't usually like to single people out, but Gar is the one that suggested adding the capacitor. So a special thanks to him.
Also to ELA who offered some of the same advise and other avenues to check also!

I don't mean to leave anyone out, so THANKS to all!!!!
!:thumbsup:
 
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ELA

Senior Member
I know another load in parallel made the unit work. Now can someone tell me what putting the capacitor parallel with the control did?
Was it mimicking a load?
It doesn't really matter as long as it worked, but I would like to know exactly how this worked.
Glad to hear you had success. One theory was noise from an offending device. If that were the issue then the idea of the cap was to shunt the noise. You disconnected all possible offenders in the area to gain some confidence that noise may not be the cause.

Another explanation is that you shortened the high frequency return path. I had mentioned to you to think about where the path was from the source to the receiver and then back to the source.

Here is a diagram to help explain. Your wall Sender being "A" and canopy receiver at B.

In some over the power line automation systems you intentionally add what they refer to as a "phase coupler" shown at "D" in order to reach devices located on the other leg/phase of the service.


They do this because otherwise the communications signal has to travel out to the distribution transformer to complete its return path.
The phase coupler mounted at the service cabinet provides a greatly shortened RF path.
Home automation users without a phase coupler would often discover that their communications worked much better when 240V loads were turned on ( dryers).

If your sending device was a three wire device it would have a relatively short return path via the neutral. Being a two wire device it becomes dependent upon other loads being turned on for a shorted return path. You added a "short cut" for the RF communications signal to return to the sender.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Thank you ELA!
I think I understand it now.

What I do understand is the customer is happy!:lol:

One other question.
What if there was something that was causing the problem and it later was not being used or replaced etc, would having the cap remain in the circuit cause any different problem?

Simply put, can the cap remain even if later it is not needed?

Well, maybe two questions. Will the cap be ok (heat wise) in the 3-gang box with it in the wall and little to no air circulating? Just trying to figure out life expectancy of the cap.
 

Sahib

Senior Member
Location
India
Simply put, can the cap remain even if later it is not needed?
It is connected across the power lines; not a load to the sending device A; perhaps no problem.
Will the cap be ok (heat wise) in the 3-gang box with it in the wall and little to no air circulating?
It depends on the relative size of the 3-gang box with respect to the capacitor. If it is spacious, convective thermal currents would be set up during the operation of the capacitor, bringing down its temperature.
 

gar

Senior Member
140525-2355 EDT

A 0.1 ufd capacitor has a capacitive reactance of about 26,000 ohms at 60 Hz, and a 1 ufd about 2600 ohms. If the power dissipation in the capacitor is about 1% of the reactive power, then there is so little heat generated in the capacitor that your finger should not detect the temperature rise.

26,000 ohms at 120 V is about 0.55 W. So dissipation in a 0.1 ufd Mylar capacitor might be 0.005 W, and in a 1.0 ufd about 0.05 W.

.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
140525-2355 EDT

A 0.1 ufd capacitor has a capacitive reactance of about 26,000 ohms at 60 Hz, and a 1 ufd about 2600 ohms. If the power dissipation in the capacitor is about 1% of the reactive power, then there is so little heat generated in the capacitor that your finger should not detect the temperature rise.

26,000 ohms at 120 V is about 0.55 W. So dissipation in a 0.1 ufd Mylar capacitor might be 0.005 W, and in a 1.0 ufd about 0.05 W.

.
Thanks!
But my question concerning heat was for the sake of the cap. I was meaning since the cap was enclosed in a 3-gang box, and the box is in the wall, would the cap survive without air circulating around it.

I see that since the cap generates such little heat that there shouldn't be a problem.
 

gar

Senior Member
140526-1031 EDT

Little Bill:

Since the heat generated internal to the capacitor is very small compared to the capacitor size the capacitor temperature rise resulting from that heat will be miniscule, and it would be difficult to measure this rise.

Much more important is that the voltage rating of the capacitor be adequate for the application. That includes expected transient voltages.

Very high harmonic content in the voltage waveform could increase the capacitor current compared to the 60 Hz component. An experiment with a Dearborn 630P 250 VDC +/-10% tolerance capacitor produced a current measurement of 10.9 mA with 123 V applied. This calculates to an impedance 11,280 ohms. The capacitive reactance at 60 Hz from my Shure Brothers slide rule is about 12,000 ohms, and a more accurate calculation is 12,057 ohms. The measured current and in turn calculated impedance is within the +/- 10% capacitor tolerance. I have some harmonic content on my voltage waveform illustrated by a somewhat flattened voltage peak. There certainly was no excessive harmonic content shown in this experiment. The 630P is a metalized polypropylene film type capacitor.

To protect a capacitor from excessive transient voltages you could parallel the capacitor with an MOV, or better with a Transorb limiter. But this also means that the capacitor voltage rating possibly should be 1.5 times the limiter maximum clamping voltage. This is going to be much above the nominal voltage rating of a capacitor just rated by peak line voltage. Unless you have a bad transient voltage problem a simple capacitor is a statistically satisfactory solution.

.
 

gar

Senior Member
140529-1016 EDT

Good reference ELA.

What this means is the choice of good materials, and then how the capacitor is rated and quality control.

A broad scope of dielectric breakdown vs material is presented at http://en.wikipedia.org/wiki/Dielectric_strength .

One MV/m translates to about 25 V/0.001", and therefore about 500 V/0.001" for a number of the materials in the list. Also breakdown is a function of time.

For polypropylene this reference http://www.goodfellow.com/E/Polypropylene.html indicates 30-40 kV/mm, or 750 to 1000 V/0.001".

Then it is necessary to determine what is really meant by dielectric strength. Life testing and material quality become important in rating an actual device.

.
 
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