Inrush current/"Bounce back" voltage 120/12v landscape transformer

[gar]

150309-2228 EDT

grasfulls:

0.1 ufd capacitors won't be polar.

With an ordinary ohmmeter, like a Fluke 27, and a high quality low leakage 0.1 ufd capacitor you will initially see a resistance value that gradually increases and becomes near infinite when the capacitor gets charged to the source voltage of the ohmmeter. Reverse the meter leads and you get the same result.

A polar capacitor can be used in a circuit where there is an AC component superimposed on a DC voltage that does not cause voltage reversal across the polar capacitor. This might be done in an audio amplifier.

You will get strange results if you put an ohmmeter across an electrolytic capacitor.

.

 

[Electric-Light]

Stop monkeying around with line voltage. You don't want to throw together some parts together that will not be UL or code.

This would work, but wouldn't do two locations like you want.

http://www.homedepot.com/p/Lithonia...d-White-Motion-Sensor-Fixture-MSX12/203995562

 

[grasfulls]

New Sensor in the discussion - not in parallel?

New Sensor in the discussion - not in parallel?

Stop monkeying around with line voltage. You don't want to throw together some parts together that will not be UL or code.

This would work, but wouldn't do two locations like you want.

http://www.homedepot.com/p/Lithonia...d-White-Motion-Sensor-Fixture-MSX12/203995562

I will read up on it. I am not sure that powering a relay or adding a capacitor across a coil will violate a UL or code, an interesting thought though. We have had EE's specify adding little things more than once, I have never given the direction much attention. We have certainly put control assemblies together where the final assembly is not UL listed.

It sure looks like that sensor has extra wiring on it and says "It is easy to install and wire to LED or fluorescent bay lights, strip lights and wraparound light fixtures." 800 watts... I see it is made by Lithonia but I cannot find it right off the bat in Llithonia. Why do you not think it could not work in parallel with another sensor?

I was reading the questions people had, one is "can it be used outdoors", a Lithonia rep actually answered "No, this sensor is not designed to be used outdoors."
:-(

 

[gar]

150311-0911 EDT

Electric-Light:

Your post made no sense other than to bring up the UL issue.

grasfulls's application requires at least two sensors connected in parallel. That is a positive logic inclusive "or" function. Second, it is an outdoor application. Third, the load is some some combination of a "transformer" (I am not sure at this time I know what kind of transformer although I was told it was magnetic.) with many LED lights connected to the transformer output. Also I don't know anything about the LED lights.

The specifications for the Lithonia sensor as to load are not much different than the specs on the units grasfulls has or is going to use, current rating is a liitle higher. But without some description of what a specific current rating means it is only a very gross indicator of capability. These specifications are totally inadequate to analyze why grasfulls has a problem.

.

 

[grasfulls]

monkeying around

monkeying around

Stop monkeying around with line voltage.

Why do you think my AVATAR is what it is.? This is like telling me to stop being me.

 

[grasfulls]

trans ID, LED ??

trans ID, LED ??

150311-0911 EDT
the load is some some combination of a "transformer"
.

TRANS = FX 229350 PotenzaX 300 (provided by landscaper)

Asked the client for specs on the lights. I would have never thought that the secondary side of a magnetic trans could impact the controls on the primary side. I have learned in here that the lights unto themselves have an inrush that may (or is it will?) add to the overall inrush of transformer start-up...more reason for a relay. I am very worried about my relay now, especially after the "wimpy" addition, but it all goes together Friday. I hope the worst case scenario is it works but I need a bigger relay, best = it all works for a long time.

A little more on the driveway lights, I sure hope they are rated for MLV and do not require a LED driver..
Crud. The client sent me a link. The fixture comes with a medium base and is made for a PAR36 lamp. The site implies an end-user may install retrofit LED lamps. I called the vendor, they never provide lamps. I now have a question into the client as to the make and model of the LED lamp.
http://www.bestqualitylighting.com/products/well-lights/lv-48/
This is like a cascade of odd sequences, but I will be a slightly better electrician before I die.

 

[gar]

150311-1329 EDT

grasfulls:

From http://www.fxl.com/sites/fxl.com/files/om_px.pdf it seems clear that this is a plain magnetic transformer with a nominial 10 t0 1 ratio, but several different secondary taps. It is not a stainless steel transformer, but rather a transformer with some relatively standard transformer steel in a stainless steel enclosure. It is not a regulating transformer as might be implied by some advertizing comments. It is sine wave in and out at exactly the same frequency.

On transformers. An ideal transformer with no losses will directly reflect load current to the primary, but scaled by the turns ratio.

We don't have ideal transformers. At least one needs to consider the transformer internal impedance. For your application the transformer internal impedance will somewhat reduce the LED peak inrush current as seen at the transformer primary. So this peak in-rush factor won't be as bad as if you had no transformer and a very low source impedance.

The actual transformer in-rush current is the superposition (addition) of the transformer core saturation pulse and the reflected LED initial peak current somewhat limited by the series internal impedance of the transformer.

The LED in-rush will be quite consistent at a given turn-on phase angle. The transformer core saturation pulse is more variable.

A relay is an important addition to the circuit from your experience so far. If you had sensors with an adequately large output switch, then a relay would be un-necessary.

.

 

[Electric-Light]

If there are two switches in parallel and it's not immediately obvious to indicate the load can be activated from two locations (as in wired like a 3 way switch), it can cause unforeseen issues with the future owner or people working on it.

Keep the monkeying on the breadboard.

 

[grasfulls]

Specs/Guidelines/As-Built

Specs/Guidelines/As-Built

If there are two switches in parallel and it's not immediately obvious to indicate the load can be activated from two locations (as in wired like a 3 way switch), it can cause unforeseen issues with the future owner or people working on it.

Keep the monkeying on the breadboard.

This seems to be a different topic, but to address it:

The need to do this was per the client. There was no way to get inputs back to the lighting system to tell the system to turn the lights on based on the input. There was a conduit to an electrical panel that also sent power down to the gate. It had spare #10's in it. We added a breaker, gave the transformer and sensors their own circuit, produced an as-built.

There is a policy/procedure document for the property that contractors are to adhere to, one is to review all drawings before proceeding to work on systems they are not familiar with. The transformer is labeled "CAUTION - POWERED BY TWO MOTION SENSOR/PHOTOCELLS, CB#9, PNL OS" Any potential future owners will have much more to deal with than the two motion sensors.

I attached an excerpt form the landscape lighting as-built (not complete) and aa blow-up of the specific transformer

 

[grasfulls]

highlight area larger pdf

highlight area larger pdf

i could see that might be tough to spot

 

[grasfulls]

SS....housinig

SS....housinig

150311-1329 EDT

From http://www.fxl.com/sites/fxl.com/files/om_px.pdf It is not a stainless steel transformer, but rather a transformer with some relatively standard transformer steel in a stainless steel enclosure.

I have always called them SS transformers, I guess it is like calling a loadcenter or a panelboard a "sub panel", I had an EE tell me sub-panels are in submarines. I think through usage terms get accepted, but you are correct, it is a transformer in a SS enclosure. I will strive to say a NEMA 3R stainless steel housed transformer. I am actually serious when I put it on a drawing, not so much in the field, I think my friends would laugh at me.

150311-1329 EDTIt is not a regulating transformer as might be implied by some advertizing comments.

I will have to look this one up as well - new topic

 

[gar]

150312-1046 EDT

grasfulls:

Stainless steel is relatively non magnetic.

In our kitchen we have a stainless knife that will attach to our magnet strip and will hold in position. If I place our high carbon steel knife adjacent to the stainless knife, then the stainless stays in place, but not much shock will knock the stainlees knife off. About 1" spacing between the the two knives.

If instead I first place the high carbon knife on the magnet bar, then it is nearly impossible to attach the stainless knife to the magnet bar. This is because the high carbon steel knife shunts a large part of the megnetic field from the bar.

The magnet bar has two steel strips with a magnet or magnets between the bars. It is about 2 ft long.

 

[gar]

150312-1143 EDT

Electric-Light:

A 2-way switch circuit is an exclusive or circuit. What does that have to do with two parallel motion sensors, an inclusive or circuit? Are you saying it is too complicated for an electrician to understand and troubleshoot.

There is no other indication that anything other than the motion sensors are controlling the lights. It is a very simple circuit, two switches in parallel that turn a set of lights on when the first of the sensors detects motion, and automatically turns the lights off after a time delay from the last trigger to one of the sensors.

.

 

[grasfulls]

Third cap, physically big

Third cap, physically big

gar:
Yes, I ordered too many because I had no idea what I should look for, then I thought I ordered ten, I get 10 sets of 5 of a rather large sized .1uf cap. They are a ocmplete waste to me... I would be glad to send
them your way. Which would be best to use, how would one begin to know?

 

[gar]

140312-2147 EDT

grasfulls:

I have an interior motion sensor, possibly Cooper. With this sensor I can control my small previously mentioned P&B relay and without chatter. This motion sensor can at least use a neutral, and I used it. Also got a Lutron motion sensor today, but I have not opened the box yet.

I am quite sure the tested motion sensor uses a contact type relay to control its output. One test for this is the voltage drop across the sensor with a 75 W lamp load, 0.025 V, and also one can hear the relay click.

For your capacitor experiment connect a couple pigtail leads to the white capacitor marked 0.1 ufd, 400 V. Put tape or heat shrink over the exposed areas. Run the experiment.

If successful, then solder your pigtails moderately close to the capacitor, find a small plastic container to contain the capacitor, and high enough that when filled with the capacitor and epoxy that everything is fully encapsulated. I would try Devcon 7814331345 which is clear and has an extended work time. I have never created a large casting with this epoxy, but it should be ok. If you had an insulating filler it would require much less epoxy.

This is still experimental. If it totally solves the problem, then you have to determine what to do about any sort of listing, or approval.

Totally how many capacitors did you buy?

.

 

[grasfulls]

Putting it together

Putting it together

140312-2147 EDT
I am quite sure the tested motion sensor uses a contact type relay to control its output. One test for this is the voltage drop across the sensor with a 75 W lamp load, 0.025 V, and also one can hear the relay click.

From the line to neutral while the sensor is active with the load attached?

140312-2147 EDT
For your capacitor experiment connect a couple pigtail leads to the white capacitor marked 0.1 ufd, 400 V. Put tape or heat shrink over the exposed areas. Run the experiment.

Why the white one? Why are those monster ones just that, monsters? Why not either of the orange ones?

140312-2147 EDT
If successful, then solder your pigtails moderately close to the capacitor, find a small plastic container to contain the capacitor, and high enough that when filled with the capacitor and epoxy that everything is fully encapsulated. I would try Devcon 7814331345 which is clear and has an extended work time. I have never created a large casting with this epoxy, but it should be ok. If you had an insulating filler it would require much less epoxy.

Uh oh, this is not getting done today, we are making connections. I was planning on inserting the pins of the pins of the capacitor into the female spade terminal with some #14 or #16 wire... I know the breaker is 20 amps and that I should introduce fused protection.... Why do you encapsulate the capacitor? Is that what both of the orange ones already are?

140312-2147 EDT
This is still experimental. If it totally solves the problem, then you have to determine what to do about any sort of listing, or approval.

To be honest, this is probably not taking place

140312-2147 EDT
Totally how many capacitors did you buy?

50 of the monsters, maybe 7-10 of the white (they are outside in the van, we are all leaving in a few minutes for the site), maybe 7-10 of the little orange ones.. I am sorta laughing while typing this because I am sure you are calling them by their technical makeup/name whereas I am using color and relative sizes. If the white ones work, I will keep them, glad to send you all the others.

Side note: I was working with a friend on a solar project yesterday and he complained about some sensors (RAB) that were hit or miss with functionality on his own home. I asked him what model, he did not know. I asked him about the load, it is some LED retrofit lamps. All I said was "you need to check that the sensor is rated for the load". You can see how "electricians" like me, we tend to just grab some things and connect them. Also, even when some may take the time to match components to their load, clients change loads down the road.

Last: The relays I have seen, whether clicking or not, have a neutral and a common line voltage. So, in the case of connecting directly to a load, like a transformer, doesn't the coil of the relay become subjected to some potential damage?

Last Last: I will post what happens later today.

 

[gar]

150313-1112 EDT

grasfulls:

From the line to neutral while the sensor is active with the load attached?

No.

Since the output switch controls the hot line, the neutral is not switched, to test whether the switch is a contact type or SCR/Triac type the voltage measurement is made across the switch with some adequate load (I used a 75 W bulb because this was enough load and was in a nearby socket.). A contact switch will have a low voltage drop, 0.025 in my test. An SCR/Triac will be in the range of 1 to 2 V. The 75 W bulb and an OAC5 SSR was 0.95 V. Measure the voltage from the hot input wire to the switched hot output wire when the output contact is closed.

Why the white one? Why are those monster ones just that, monsters? Why not either of the orange ones?

I like axial lead components. The dielectric material determines size when other factors are the same.

Uh oh, this is not getting done today, we are making connections. I was planning on inserting the pins of the pins of the capacitor into the female spade terminal with some #14 or #16 wire... I know the breaker is 20 amps and that I should introduce fused protection.... Why do you encapsulate the capacitor? Is that what both of the orange ones already are?

All the capacitors are encapsulated. After attaching insulated wire leads to the capacitor leads and potting that assembly the result would be completely enclosed package. Safety and a possible means of mounting the capacitor.

50 of the monsters, maybe 7-10 of the white (they are outside in the van, we are all leaving in a few minutes for the site), maybe 7-10 of the little orange ones.. I am sorta laughing while typing this because I am sure you are calling them by their technical makeup/name whereas I am using color and relative sizes. If the white ones work, I will keep them, glad to send you all the others.

Without more information color and size are good discriptors.

.

 

[grasfulls]

It works - sweet! Now for the test of time

It works - sweet! Now for the test of time

gar:
We connected it, it is working, but not without a few oddities.
First, I used the small orange capacitor ( I had to leave before hearing back and had to make a choice, I was worried about the paper one not being encapsulated)
I slid a heat shrink onto the metal "legs" leaving enough exposed to slide into a female spade terminal.
I put the ends into terminals with a stranded #14, crimped and then soldered the connections.
Shrink the heat shrink
I tried two of the original sensors, lottsa chatter on activation.
I tried the new RABs, they clicked and everything worked great.
I do not know if they would have worked without the capacitor.

You have been an awesome help and a wealth of info. So, do you want all of the capacitors? Do you want something like 6 different motion sensors? I will gladly ship, otherwise they will just disappear.

 

[gar]

150314-0915 EDT

grasfulls:

About capacitors and sensors I will PM you.

Yesterday, also the day before, I stopped at Home Depot and Lowes to look at electrically related items with respect to your problem. Day before yesterday I encountered a totally ignorant electrical salesman. One example, he did not know the difference between AC and DC.

The first day I bought the Lutron motion sensor. I could not find a low voltage LED PAR-anything 12 V bulb at that time.

Yesterday I found a somewhat more informed salesman. They don't have any LED PAR-36 bulbs.. So I bought a Malibu LED Floodlight. No voltage spec other than Low Voltage, 11 watts consumed, 300 lumens, equivalent to 50 W halogen, no indication whether AC or DC or both. Half of the presented information is in Spanish. That we don't need, but what we need is not there.

This morning a quick test on the Malibu 11 W LED, this is not well instrumented. I used DC from one of my supplies with a 53,000 ufd output capacitor. Steady-state was 0.9 A at 12 V. Peak inrush using eyeball looking at scope was about 80 A with a time constant of about 0.5 to 1 millisecond. A typical RC exponential curve.

Scaling this to your 150 W would make the low voltage peak possible inrush about 13.6*80 = 1088 A. Divide this by 10 from your transformer ratio and the peak primary current might be as high 100*1.4, or 140 A. But this is limited by circuit resistance, and transformer leakage inductance. To this we might add the transformer inrush current.

This high of a peak should not occur because many factors have to occur simultaneously.

I need to run more experiments, but that is unlikely to occur soon. Your problems do point out the need for a better understanding of the problems and solutions. Thermister current limiters could be partial solution.

.

 

[gar]

150315-1440 EDT

grasfulls:

My guess is that the RAB units would work without the capacitor, but might have shorter relay contact life. I believe the reason RAB suggests the capacitor is to reduce contact arcing at their relay contacts at turn on from contact bounce, and contact opening at turn off. The capacitor is a snubber. That you heard a click in the RAB unit implies a mechanical contact output switch.

I am interested in your other sensors to see if I can determine what failed.

I would accept the capacitors, but you certainly should keep an appropriate number. In the old days capacitors like these were made with aluminum foil as the capacitor plate and paper as the insulator. Between about 1940 and 1950 paper began to be replaced with plastic film like Mylar and for special purposes polystrene. Later came polypropylyene and others. Mylar was a better insulator than paper. Then came metalization, early to mid 1950s, instead of aluminum foil. Sizes were reduced and life improved.

I will PM.

.