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Traffic Signal Load Switches
These go inside the cabinet and switch on the signal indications by -24v, + ground. I opened some to show the insides. The small cube in upper right is a switching module from one like the top left, it contains 3 (RYG).
Keywords: Gear

Traffic Signal Load Switches

These go inside the cabinet and switch on the signal indications by -24v, + ground. I opened some to show the insides. The small cube in upper right is a switching module from one like the top left, it contains 3 (RYG).

CIMG2946.JPG image~33.jpeg CIMG9456.JPG GE_weld_fail.jpg TOR_IMG_2085.JPG
File information
Filename:CIMG9456.JPG
Album name:rlshieldjr / Traffic Signals
Keywords:Gear
Filesize:65 KiB
Date added:Apr 15, 2013
Dimensions:800 x 560 pixels
Displayed:682 times
Color Space:sRGB
Contrast:0
DateTime Original:2013:04:12 20:38:08
Exposure Bias:0 EV
Exposure Mode:0
Exposure Program:Program
Exposure Time:1/60 sec
FNumber:f/2.8
Flash:Flash, Auto-Mode
Focal length:6.2 mm
ISO:64
Light Source:Unknown: 0
Make:Casio Computer Co.,ltd.
Max Aperture:f/2.8
Model:EX-Z9
URL:http://www.galleryoflights.org/mb/gallery/displayimage.php?pid=15449
Favorites:Add to Favorites

Comment 1 to 4 of 4
Page: 1

rjluna2   [Apr 15, 2013 at 11:25 AM]
Thanks for sharing the guts of these traffic signal modules to us Smile
joe_347V   [May 10, 2013 at 03:31 AM]
I'm guessing these are solid state?

Anyone know if they once used relays in these load switches?
I could have sworn I heard a cabinet click when the indications changed but I'm pretty sure that cabinet didn't have an electromechanical controller.
SeanB~1   [May 11, 2013 at 08:57 AM]
Mechanical relays or optical are used. Both have about the same life, 100 million cycles. The relays tend to wear out either from contact wear or from the actual contacts or core breaking up from fatigue, generally failing open circuit. The electronic ones though tend to fail as a short circuit, especially if the output is shorted and the fuse is the wrong type or value, or the breaker fitted is slow. Typically you always have a relay contact to allow the conflict monitor to override the controller and switch the outputs off and switch in a flashing signal to the appropriate lights.
rlshieldjr   [Jun 10, 2013 at 12:29 AM]
The clicking sound may be from a detector. Some of the older load switches have reed relays to isolate the 120v from the 24v controller. Newer load switches have a "Zero-Crossing" circuit to star the ON cycle when the sine wave is at zero volts, helps extend incandescent bulb life.

Comment 1 to 4 of 4
Page: 1