Lighting Contactor Issue

[GoldDigger]

With the engineer's information update the measurements should be...

Line to Neutral: 240V at all times

Night:
Line to Load ~0V
Neutral to Load ~240V

Day:
Line to Load ~480V
Neutral to Load ~240V


You are correct. At night, you should have measured ~480V from receptacle Load terminal (wired to one side of contactor coil) to other side of contactor coil, and ~0V from receptacle's Line to Load.

But since you stated that test point 3 was at the contactor coil, not at your control, it does leave the possibility that the engineer was reading the wrong side of the coil. In that case 480 volts makes perfect sense.

 

[Smart $]

But since you stated that test point 3 was at the contactor coil, not at your control, it does leave the possibility that the engineer was reading the wrong side of the coil. In that case 480 volts makes perfect sense.

You quoted my post but your reply refers to one of and seems to be a statement to the OP'er... :?

Other than that, I agree. Across the coil at night 480V, during day 0V.

 

[GoldDigger]

You quoted my post but your reply refers to one of and seems to be a statement to the OP'er... :?

Other than that, I agree. Across the coil at night 480V, during day 0V.

Sometimes I am still challenged by the multi-quote system. Everybody looks the same to me from here, and some of my best friends are electricians.

 

[hurk27]

With the engineer's information update the measurements should be...

Line to Neutral: 240V at all times

Night:
Line to Load ~0V
Neutral to Load ~240V

Day:
Line to Load ~480V
Neutral to Load ~240V


You are correct. At night, you should have measured ~480V from receptacle Load terminal (wired to one side of contactor coil) to other side of contactor coil, and ~0V from receptacle's Line to Load.

The OP mention that this is a fail on system in post 11, which would be a N/C contactor so it would be energized during the day to turn off the lights and not energized at night to turn on the lights, and would explain why he is seeing 480 volts across the line and load during the night, in a fail on system everything is swapped so if the contactor coil were to fail the lights would stay on.

The reason he is seeing 480 volts across the 2&3 test point at night is because his controller contact is open, the reason he is seeing 240 volts between test points 1&3 is because he is reading the other leg of the 480 source through the coil of the contactor, if you were to swap the day and night diagrams above you will see that he has a fail safe system and the readings make sense, as I tried to point out in post 14 second paragraph

 

[Smart $]

The OP mention that this is a fail on system in post 11, which would be a N/C contactor so it would be energized during the day to turn off the lights and not energized at night to turn on the lights, and would explain why he is seeing 480 volts across the line and load during the night, in a fail on system everything is swapped so if the contactor coil were to fail the lights would stay on.

I think you misread. As I understand it, the controller's integrated relay is fail on, i.e. NC contacts. The lighting contactor itself is fail off.

 

[hurk27]

I think you misread. As I understand it, the controller's integrated relay is fail on, i.e. NC contacts. The lighting contactor itself is fail off.

Well then the readings do not make sense, I have worked with fail on interstate/toll road lighting controls before, and the main contactors are NC, many lighting contactors are switchable from N/O to N/C type for fail on systems, so I'm at a loss at to what he has be cause his readings are saying he has a fail on system?:?

 

[Smart $]

Well then the readings do not make sense, I have worked with fail on interstate/toll road lighting controls before, and the main contactors are NC, many lighting contactors are switchable from N/O to N/C type for fail on systems, so I'm at a loss at to what he has be cause his readings are saying he has a fail on system?:?

I understand what you are saying, and made a statement to the same effect back in post #12...

Taking into consideration your posted readings...

...it seems to me your readings are backwards...

However, I am going by post #11....

The relay in the controller is normally closed (fail-on for safety). The controller opens the relay during the daytime.

...

A fail-on lighting contactor, with NC contacts, cannot be energized solely by this controller in series with the contactor's coil.

 

[hurk27]

And we have the ability in the field to make the controller think it's day or night to put the relay in whatever state we want to measure voltages in.

A fail-on lighting contactor, with NC contacts, cannot be energized solely by this controller in series with the contactor's coil.

From the above statment in post 11 I took as the controller could be used in a fail ON system or normal system, that is is switchable? not sure though?

 

[hurk27]

But his readings are still telling me he is energizing the contactor during the day and turning it off at night?

 

[Smart $]

From the above statment in post 11 I took as the controller could be used in a fail ON system or normal system, that is is switchable? not sure though?

And I took it to mean the integral relay was fail on, contacts NC and energized during day, deenergized at night.... while the ability to make the controller think its day or night in the field was the same as most any photocell controller, cover "eye" during day, or use a flashlight at night. Isn't this the industry standard for a lighting controller with a single set of contacts?

But his readings are still telling me he is energizing the contactor during the day and turning it off at night?

And I agree that's what the reported measurements indicate.

 

[hurk27]

From the above statement in post 11 I took as the controller could be used in a fail ON system or normal system, that is is switchable? not sure though?

And I took it to mean the integral relay was fail on, contacts NC and energized during day, deenergized at night.... while the ability to make the controller think its day or night in the field was the same as most any photocell controller, cover "eye" during day, or use a flashlight at night. Isn't this the industry standard for a lighting controller with a single set of contacts?

But his readings are still telling me he is energizing the contactor during the day and turning it off at night?

And I agree that's what the reported measurements indicate.

Except that I know the controller he is using, it's not a photo cell, it is a GPS based system that uses the clocks from the GPS system as the base timer to turn on and off lights as a controller, kind of ingenious if I might say so.

Here is the first threads he posted and has links to the company he works for:

http://forums.mikeholt.com/showthread.php?t=149430


Applied Physics Laboratories
And heres a link to a PDF that shows a little more about it:

http://www.physics.us.com/uploads/Cut_Sheet_Rev1.pdf

Which does not indicate any kind of reversed switching?

So not sure what all this controller is capable of or if it has a switch to change it from a N/O to a N/C controller?

 

[mgookin]

When a relay switches a relay, there's bound to be confusion, and that's the case here.

Our Controller
Our controller is normally closed to create a fail-on condition when used on a single cobra head.
Many contactor cabinets have a twist-lock receptacle to control the contactor via one of these industry standard twist-lock controllers, and that's the case here. We switch (our customers switch) plenty of 240/480V contactors with no problem using our 120-277V controller. We have installations in North & South America, Europe, & Australia/ New Zealand on both 50Hz & 60Hz grids without a failure except this one installation. In the daytime our controller has to supply 24VDC to our relay to open the contacts and turn the lights off. At night our controller stops supplying 24VDC to the relay to allow the NC contacts to turn the lights on, and this causes the contactor coil to become energized.

Contactor
The contactor coil is normally open. At night when the controller relay is closed, the contactor coil is getting power and closing the contactor thereby turning the lights on.

The voltage measurements we took were only from where the controller receptacle leads, which are white, black & red, connect inside the cabinet. We never probed an empty receptacle and we never probed anything other than white, black & red leads. I'm still at a loss as to how we measure 480V black to red (line to load) at night when effectively what is happening is our controller is connecting those two conductors via the relay. If our controller was connecting two 240 legs of a 480 system, shouldn't there be fireworks inside that cabinet? Is something wired wrong inside there, or am I still misunderstanding this?

Thanks.

 

[mgookin]

Except that I know the controller he is using, it's not a photo cell, it is a GPS based system that uses the clocks from the GPS system as the base timer to turn on and off lights as a controller, kind of ingenious if I might say so.

Here is the first threads he posted and has links to the company he works for:

http://forums.mikeholt.com/showthread.php?t=149430


Applied Physics Laboratories
And heres a link to a PDF that shows a little more about it:

http://www.physics.us.com/uploads/Cut_Sheet_Rev1.pdf

Which does not indicate any kind of reversed switching?

So not sure what all this controller is capable of or if it has a switch to change it from a N/O to a N/C controller?

Thanks for the compliment. It's a N/C controller with no reversed switching. It would be simple to make it a N/O controller but we have other projects ahead of that and nobody's ever asked for N/O.

We have a 480V rating in development. There is little market for that relative to the 120-277 market.

A major lighting manuf. has asked us to redesign the pcb so that the only thing on top is the antenna. They'll put it in their 100,000 hour LED cobra head to reduce warranty exposure and assure the customer gets the energy savings they expect. It seems when they get complaints that customers are not realizing the energy savings they expected, the manuf. rep will visit the site and find the lights on at 10:00am because they use the same controls that burned up their last equipment. This control makes sure the lights only switch once per day and they never burn when the ambient light level exceeds that produced by the luminaire. For utility scale installation it offsets inrush (2 meter accuracy) and predicts their demand (we wrote the algorithms so we can tell them when it's going to switch based on lat, long & date).

It's been a fun project. We passed UL the first time through on both engineering and initial factory inspection.

Thanks again for all the assistance.