Traffic light problem

[Ken9876]

We have a traffic light that is blowing a 1 1/2 slow blow fuse to the controller. It does this intermittly, I went out to the job and connected a fluke 434 power quality meter which I'm still learning to use and understand. In the tranisits mode it picks up a tranisit almost everytime the signal goes to highway amber which would be the most load on it. The meter is showing during the negitive half of the cycle while rising back to 0 volts, the voltage will go from -42 volts to 9 and back to -12, right after this happens the current goes up to 60 amps and drops back down, this all occurs in maybe 3 cycles. I have not had the fuse blow while there. The POCO has been out and reconnect all our service wires at the pole, and this problem still continues. Anyone have any ideas on my problem or insights? I'm still trying to understand what this meter is telling me, have been doing alot of reading.

 

[robbietan]

looks like you have monitored switching transients. fuses should not blow due to these (especially slow blow ones).

 

[LawnGuyLandSparky]

Wat kind of controller, and is this controller monitered by an RCU or a mod kit?

 

[Ken9876]

I need to check on the controller type, I belive it's a peek or transit I need to check, NJ buys from everyone, The controller is monitored by a voltage monitor. It's a simple two phase intersection. This isn't my area the guy who takes care of it has been replacing fuses and three controllers have gone bad at this job, Need to find out why. Talked to him the trouble seemed to stop after the first time the POCO redid the connections which was in September and the troubles have recently restarted with the warmer weather. Which makes me think maybe the incoming power has something to do with it.

 

[wirenut1980]

Can you monitor voltage on the AC side of the service point? If not, I would request that the POCO set up a recording voltmeter at the service point to see if they have flicker or sag problems.

 

[S'mise]

I am never worked on traffic controllers but I would start by examining the cables where there is flexabillity (field wiring to light). Sounds to me like an intermitten short in the cable is taking out your controller. I have seen cases where a poor connection or bond to the controller causes a rouge ground thru interconnect cables which in turn will fry the controller. The warmer weather problems point to this also because resistance is higher. I would Not think a small sag in your line voltage would be an issue taking out that fuse. See if it has diagnostics features that will tell you what the last failure was. (power loss, short circuit..ect.)

 

[tom baker]

I've worked on traffic signals for almost 20 years and am IMSA Level II TS certified.
I have never seen a fuse blow on the controller.
A few questions:
Is there a seperate 24 VDC power supply, or does the controller supply DC power to the load switches.
What is the conflict monitor telling you? Does it show a DC fault?
The displays are typically controlled by load switched, the controller operates the load switches, usually a logic ground. Have you replaced the load switches?
Can you install a different controller?

 

[Ken9876]

Tom,
This is a TS 2 setup standard two phase job, the controller supplies its own 24v power, and for all the logic and load switches. This is not my job I'm only going by what the guy who's job it is is telling me, which is the fuse has blown many times, they have put in three controllers, all the same model though, the controller is a transyt 1880 I belive.
We Installed a small voltage recorder, that will be brought back to the shop in a while.
This all seemed to start after a POCO light pole was hit, they did not replace the pole but rather, cut it down and the three wires coming from the pole suppling our service. The wires are hanging in free air and blowing around. The fuse stopped blowing after we pulled a new lateral and the POCO reconnected in September, however we are starting to have the same problem which leads me to belive it's the POCO and they don't want to do a damn thing. The transformer is buried in the woods vines are growing all over the transfomer, primary and secondary conductors, Really a complete mess.