PDA

View Full Version : LED interference?


shovelracer
11-20-2011, 06:32 PM
We recently did a job that entailed 47 Kichler LED fixtures. We intended to tie it into the homes existing Zwave home automation for control. When the system is not hooked up the Zwave controls well through walls, the deck, etc. When the system is on the Zwave tanks. If you stand outside the area with a remote it seems to work fine even from 50-70' away. The closer you get to the center of the systems zone, in the middle of the landscape it works maybe once out of ten. Even at 5-10' away from a remote switch there is extremely poor performance. Now the problem is that this system is all around the back so the kitchen which is pretty much in the middle is suffering. The Zwave does not function as it did prior in the back rooms, primarily the kitchen which is in the center.

I have contacted the companies of the various products and no one seems to have a fix. Has anyone had any issues with this? We are going to control the landscape zones with hardwired controls now, but we still have an issue in the back rooms. The only thing I can come up with is to get away from the Zwave and go with a different system.

steveparrott
11-21-2011, 07:07 PM
It's quite likely that electromagnetic interference (EMI) generated by the LED's is the problem. Very few LED manufacturers (CAST is one of them) add components and circuit designs to eliminate problematic EMI.

This is a known problem and has been discussed in this forum several times - mainly with garage door openers.

Z-Wave is a radio frequency (RF) system and while it has automatic protocols to deal with some interference, it probably can't handle close proximity to high-power LED circuits that do not have EMI filtering.

The only solution is to replace the problematic fixtures with incandescent or with LED's from a manufacturer with EMI filtered circuits.

steveparrott
11-21-2011, 07:20 PM
Another solution just occured to me - you could power the fixtures with DC instead of AC. It is the LED switching rectifier that generates the EMI as it flips the AC wave over into a DC current. When DC is applied, that switching doesn't happen and little or no EMI is generated.

Most LED's work fine (better, in fact) with DC - you'll need to check with Kichler to be sure. Also keep in mind that DC tends to increase the forward voltage through the LED chip, generating more heat, and reducing it's life, and more importantly, reducing the life of the capacitors. Reducing the voltage to 9 or 10 volts might be a good idea.

lilmarvin4064
11-21-2011, 08:46 PM
Another solution just occured to me - you could power the fixtures with DC instead of AC. It is the LED switching rectifier that generates the EMI as it flips the AC wave over into a DC current. When DC is applied, that switching doesn't happen and little or no EMI is generated.

Most LED's work fine (better, in fact) with DC - you'll need to check with Kichler to be sure. Also keep in mind that DC tends to increase the forward voltage through the LED chip, generating more heat, and reducing it's life, and more importantly, reducing the life of the capacitors. Reducing the voltage to 9 or 10 volts might be a good idea.

Yes, I would think the drivers would be the culprit, not the LEDs. You could add just a single high current bridge rectifier in the transformer or get a whole new transformer all together. If the drivers are properly designed, they should supply a constant current, not a constant voltage, so supply voltage would be insignificant as long as it is in range. Voltage doesn't kill an LED as easily as current does. If the LED drivers on those Kichler fixtures don't accept DC without issues, then there is a major design flaw!

But the best solution would be to upgrade the home automation system to Bluetooth. RF is so oldschool; too many issues.

oberkc
11-22-2011, 06:50 AM
Another clue might be if the Z-wave devices reliably turn the lighting system from OFF (LEDs unpowered, no interference) to ON, but have diffuculty turning them from ON to OFF. If there are problems in both cases, my tendency would be to look for causes other than RF interference from LED lamps.

But the best solution would be to upgrade the home automation system to Bluetooth. RF is so oldschool; too many issues.

I thought Bluetooth was RF?! I expect a better solution would be to use UPB or insteon or, even, X-10, if RF interference proves to be the case.

steveparrott
11-22-2011, 06:35 PM
I thought Bluetooth was RF?! I expect a better solution would be to use UPB or insteon or, even, X-10, if RF interference proves to be the case.

If a wireless remote control device is used in the UPB system (such as with Pulseworx or Controlscape) then RF is still involved - still a problem. Most UPB systems (and Insteon's USB) use RF for their wireless controls.

X-10 is out of business.

oberkc
11-23-2011, 06:33 AM
Most UPB systems (and Insteon's USB) use RF for their wireless controls.

Just to be clear, Insteon and UPB communicate primarily over the powerlines. While they may communicate via frequencies that are within the radio spectrum, communication is not via radio waves. Some Insteon devices include a secondary communication path by radio waves. These are known as "dual band" devices.

I believe it a near certainty that they are not as succeptible to RF inteference than Z-wave, though they are not without their own set of potential communication problems.

While X-10 may be going out of business, X-10 enabled devices are still available.

shovelracer
11-24-2011, 07:32 AM
Another clue might be if the Z-wave devices reliably turn the lighting system from OFF (LEDs unpowered, no interference) to ON, but have diffuculty turning them from ON to OFF. If there are problems in both cases, my tendency would be to look for causes other than RF interference from LED lamps.



I thought Bluetooth was RF?! I expect a better solution would be to use UPB or insteon or, even, X-10, if RF interference proves to be the case.

This is part of the issue. Off -On is better than On - Off. Infact on-off has never worked properly with relation to what were talking about. There are difficulties though with off-on as well. I suspected perhaps the transformer was playing a role as well since it is effectively on and being controlled internally. Also there are several zones and pieces. Some work much better than others. I also suspect this has to do with their frequency.

oberkc
11-24-2011, 09:48 AM
Given that your problem appears worse when going from on>>off tends to support the theory that there is some type of radio interference with Z-wave caused by the LED lamps.

I would be surprised if the transformer, itself, being powered interfered with the Z-wave devices. I suppose it is possible, however. Unfortunately, transformers CAN cause problems with insteon and UPB by spewing noise onto the powerlines. Fortunately, they make filters for this type of thing.

Are these the types of fixtures with the integrated lamps? If so, it would be diffucult to further troubleshoot by removing some of the LEDs to see if this helps. I am curious how, or if, your problems would be affected if you temporarily disconnected the transformer from the LED lighting circuits.

S&MLL
11-24-2011, 01:28 PM
Zwave is your biggest problem. Get your H.O. to go upb. Using my ambience or some sort of itunes software. An ipad over IEEE should not have same problem