power spike removal
power spike removal
(OP)
Not sure if this is the right place for this as it involves a couple things.
I have an oil burner on a rural electric supplier. It is a vacation home and the temp is at a minimum when vacant.
The issue is the reset keeps tripping - occasionally when someone is there to reset it. Last year we broke 2 toilets because it stopped in dead cold weather.
I have tried everything to stop it. My conclusion now is that it is power spikes on the line getting thru to the triac that trips the breaker.
All burner flame out circuits are the same and there is no devices on them to prevent this. The power company says they can't monitor for short power interruptions or spikes. I have a TD relay on the input neutral side which trips in 10ms, then resets in 3 min. The oil control trips in about 15 sec for a flame out (a little short of the 30 sec spec).
The motor and HV xfmer supply runs thru the line input which is why the TD relay it in the neutral.
SO, is there a reasonable why to suppress these transients either externally or with a circuit mod?
Attached is the schematic.
thx
bill
I have an oil burner on a rural electric supplier. It is a vacation home and the temp is at a minimum when vacant.
The issue is the reset keeps tripping - occasionally when someone is there to reset it. Last year we broke 2 toilets because it stopped in dead cold weather.
I have tried everything to stop it. My conclusion now is that it is power spikes on the line getting thru to the triac that trips the breaker.
All burner flame out circuits are the same and there is no devices on them to prevent this. The power company says they can't monitor for short power interruptions or spikes. I have a TD relay on the input neutral side which trips in 10ms, then resets in 3 min. The oil control trips in about 15 sec for a flame out (a little short of the 30 sec spec).
The motor and HV xfmer supply runs thru the line input which is why the TD relay it in the neutral.
SO, is there a reasonable why to suppress these transients either externally or with a circuit mod?
Attached is the schematic.
thx
bill






RE: power spike removal
RE: power spike removal
I'm not sure why you think it's transients tripping it off. You say it's tripped-off while someone was there? It wasn't during a start? What is the normal "abnormal event" that's supposed to cause the trips?
Keith Cress
kcress - http://www.flaminsystems.com
RE: power spike removal
When it is running it seems like the circuit is primed so that a spike coming thru there causes an immediate reaction as opposed to the 15 sec delay. I'm not sure that is design intent, but I think that is what happens. Normal operation depends on the RC constant.
Maybe a bidirectional Transient suppressor diode on the secondary of the transformer?
RE: power spike removal
How much does this furnace draw when running? Got a motor nameplate picture or manual page that would tell us?
I expect what you really need is a UPS.
Keith Cress
kcress - http://www.flaminsystems.com
RE: power spike removal
If I put a TSV across the xfmr, the point is to kill any transients under 10ms.
It is cheap. So as an experiment it is not an issue. I think I have tried everything else except installing enough electric heat to ward off the freezing. I set the furnace at a min 50 deg, so if the elect is set @ 45 it will only operate if the furnace fails.
RE: power spike removal
Your fallback electric heat scheme is a good one. Especially since it's so easy to implement. It leaves you exposed only to a power failure.
Everyone I know skips the heating because power failure during an especially cold storm is often a given. All my friends with cabins have a little check list for leaving:
1) Turn water off.
2) Drain pipes. (They use the lowest exterior faucet.)
3) They flush the toilets after turning the water off.
4) Pour a cup of eco-antifreeze into the toilet bowls.
Keith Cress
kcress - http://www.flaminsystems.com
RE: power spike removal
Thx
RE: power spike removal
Sink traps I forgot about.. His instruction included them. I don't have a cabin. :/
Exterior plumbing that's not deeply buried you have two choices on. Heat tracing with insulation or running the water. I'd probably put a few temp sensors in strategic plumbing places and when the temp gets down to 34F open a valve and run the water somewhere. The 55F well water will take a long while to cool down to 34F again. If a certain pipe or tank is found to reach 34F first and long before anything else then insulate it. That covers the pressure tank. Insulate it too to keep the water cool in the summer and warm in the winter. Or heat trace it too.
Keith Cress
kcress - http://www.flaminsystems.com
RE: power spike removal
But-- There were no "Power Surges".
Fortunately the mitigation schemes were also effective for the real problem.
The problem? Low voltage. Power outages were common on Sundays. The utility crews killed a lot of circuits to do maintenance.
The distribution was four wire circuits with transformer primaries connected phase to neutral.
A common scheme for industrial plants was a four wire Y:d connection.
That's where I learned to hate the delta.
The transformers were fuse connected with fused cut-outs. When the power was restored by closing a fused cut-out, one phase would be happy, but the other two phases would be back fed trough the wye:delta banks and two phases each developed approximately half voltage.
All the compressors would try to start but on 50% voltage would stall.
A basic hot stick has a peg with a mushroom head sideways on the end. The telescoping stick may be 25 feet long. The peg is inserted into a ring on the fuse holder and used to raise the fuse holder into position and then the peg must be carefully removed from the hole without knocking the fuse holder to the ground. The peg is then inserted into a second ring (about 25 or 30 feet in the air) to close the fuse holder. Then the lineman must carefully remove the peg from the second ring on the fuse holder. Then the fuse holder for the next phase is raised and inserted the same way.
Not a fast operation.
In the meantime, 2/3 of the compressors on the circuit are sitting stalled with 50% voltage applied.
What's the pint? Well if you are trying to suppress surges when the real problem is voltage surges, good luck.
Voltage sags are a fact of life on long rural lines. Relays and contactors tend to drop out during voltage sags. When the device drops out the impedance drops and the current goes up, and the coil may burn out, or the fuse or breaker may open.
This may be your solution.
It protects against both high and low voltage.
When healthy power returns there is a three minute safety delay before power is returned.
As I mentioned these were installed to protect against non-existent "Surges" but actually saved the compressors by protecting against the low voltages.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
Anyway, if you look at the crt. you see that if the 24v drops that reset may never trip. The sensor drops the voltage across the cap when it sees flame. If the flame quits the voltage rises and trips the triac. That heats the heater tripping the relay which cuts the motor and HV xfmr out. If the 24v is low, the trigger V may not get high enough. But that wouldn't be good so I am sure they designed for that. The sensor goes from over 100k down to about 5k I think. So it probably would get to trip V anyway. I may not get to test the TSV this year. It will be a while b4 I get back up there.
RE: power spike removal
Yes, you are soo right. There are so many people telling each other about spikes that it becomes a truth. I still try to get a recording of one of those spikes. I really never found one that was powerful enough to kill anything like a relay coil, a thyristor or triac or even a photo resistor.
But I have found many brown-outs and fast-and-short drops that reset relay circuits or upset mico-processors without causing a proper reset, which kicks them into never-never land.
Recorders not fast enough? Not tried enough times? Pls, don't insult me. Been in this business for more than half a Century and used TEK digital scopes (also used their analog memory scopes, remember?), HIOKI and Siemens recorders, BMI and Dranetz and many other equipment to record that elusive "spike" without getting anything better than around 200% overvoltage in the us range or 50 - 70% of sine peak in the ms range. I have met hundreds of field problems that were supposed to be caused by "spikes". Yes, some were, but then it was elaborate overvoltage protection in paper machine drives or gas turbine plants that over-reacted. Not your standard automation system that was in any way killed by the spikes.
Once again, Bill: You are soo right. PLS for you.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: power spike removal
Such kind words from someone of your education and experience are more valuable to me than a multitude of PLSs.
How many times have we both been the second or third or fourth person called and found that in addition to fixing the problem, we have to undo several other problems that were someone else's attempt to fix the wrong problem.
How do we make the point that the very first step in effective problem solving is to determine what the problem actually is.
An anecdote, true story, to illustrate waste and futility of fixing the wrong problem.
I was working on a panel and nearby some mechanical guys were replacing a 3 HP motor with a belt drive to a fan.
They started the fan up but something didn't look right. They stopped the motor and found that it had "Gone out of alignment".
They readjusted the motor base and tried again. Again it had "Gone out of alignment".
A third man showed up to help.
Try again.
Again, "Gone out of alignment".
This was repeated all day and all the second day.
At one point the motor was found to be tilted. The amount of tilt was carefully measured and they were gone for awhile.
They returned with a wedge to put under the motor so as to be able to properly align the drive.
Start, stop. "Gone out of alignment!"
Midway through the third day, someone discovered that the pulley was cocked on the motor shaft.
When the pulley was installed on the replacement motor the bolts on the taper lock hub had not been tightened evenly.
The fix?
Remove three bolts and insert them in the jack screw holes.
Remove the pulley.
Reinstall the pulley properly.
Check the pulley for square with the shaft. Always the first step in an alignment job.
Time? 15 to 30 minutes for one man.
Time actually wasted, about 7 man days.
Again.
The very first step in effective problem solving is to determine what the problem actually is.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
Waross, DUH! you can't determine what the problem really is if you are a parts jockey. And most people won't pay the price for an engineer to figure it out. Have you called for technical support on your computer, ever? It is all about asking the right questions, logic, thinking, and testing skills which you can't get from someone you hire off the street corner. My brother-in-law thinks......he is smart, but it is self-deception. He called a "professional" to fix the burner when I told him I would handle it. Guess what, the pro had no clue, admitted he was an AC guy from SC and just moved to NC and really didn't know oil burners. So who fixed it, me of course.
So, proof that it takes more than thinking.
A final question....I don't know what I should use for the breakdown voltage of the TSV . I'm thinking 40V to cover line variations up to 130V, 36V (actually 36.7) would be closer if the input stays below 130. What is your experience with rural line voltage variations?
RE: power spike removal
I think you're looking at a UPS or a CVT to actually fix the issue. Or else changing/modifying the system with a design that works better when subjected to the power isssues your vacation home.
RE: power spike removal
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
I am not reading that 3 people are saying it is NOT a spike. But I may be totally missing something. If you can define the failure mechanism for something other than a spike then I would be oh so glad to investigate it. AND you can be VERY technical as I am a BSEE.
RE: power spike removal
Based on its history, and the fact that it only happens when there are power anomalies, my conclusion is the control is OK.
RE: power spike removal
Are you asking for advice? Or not?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: power spike removal
RE: power spike removal
If you think it is a spike, then get a transient analyzer and measure the spike.
RE: power spike removal
That said, are you saying you want to put it on the 24V side or a low voltage side? That's superior because then it gets to work with the transformer's considerable impedance. What is the nominal voltage you want to put it across? Are you specifically going to use a Metal Oxide Varistor? (MOV) Or something else?
Keith Cress
kcress - http://www.flaminsystems.com
RE: power spike removal
RE: power spike removal
Re-closer events are common on long rural lines, particularly if the roads are narrow and tree lined. A re-closer trips the line off circuit when there is a fault on the circuit. The most common fault on a rural line is tree branches or large birds across the line. The second most common fault is failed transformers.
The typical operation of the pre digital re-closers was 3-5 seconds off and and then back online. If the fault was still re-closer would immediately trip open for another three seconds. It would re-close three times hoping that the tree branch or bird would drop free. If this did not clear the fault, then a failed transformer was suspected. The re-closer would close back in for a longer time, sufficient to blow the fuse on a shorted transformer and clear the line. That would happen twice. a total of 5 operations. The re-closer stays open after the 5th try. If you are downstream from a re-closer you may experience several outages of a few seconds duration in less than a minute. If you are fed from a small rural substation, a re-closer event on an one circuit may cause voltage dips on the other circuits out of the sub.
Try tripping the power off and on at 3 second intervals. If your circuit trips you have found the problem.
I thought that I had already posted this link but I don't see it. Sorry, here it is now.
http://www.ebay.com/itm/Refrigerator-1800-Watts-Vo...
This will protect against spikes and surges.
It will also protect against low voltage and the three minute safety delay will protect against re-closer events.
The problem may be low voltage or re-closers, but you can put this surge protector on and if it fixes the problem that must prove that there were surges, right? (Even if there never were any surges.)
It always proved it to the customers in the third world.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
Keith Cress
kcress - http://www.flaminsystems.com
RE: power spike removal
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: power spike removal
The circuit basically has the safety switch contact, thermostat, relay coil, safety switch heater and triac all in series. When the thermostat calls, it starts out with the triac triggered which pulls-in the relay. The relay energizing causes it to latch itself via relay contact #1 and to start the burner via relay contact #2.
The relay #1 contact makes the circuit so the safety heater and triac are in series across the power. Once a flame is detected, the flame detector turns the triac off which stops current from flowing through the safety switch.
So, even is a "spike" triggered the triac on, it would go back off within a cycle of the AC voltage, which is a far shorter time for the current to flow then the safety switch should require current to trip.
Know the above, it certainly appears the circuit does has an issue. The safety switch should not be tripping instantaneously and should never trip from a single cycle of the triac being noise triggered on.
I gathered this from a 10-minute look at the circuit. During this look, I also determined that the diagram you posted shows relay contact #1 wrong - it should go to a center tap on the transformer, otherwise the circuit simply can't work. But, I'm sure a BSEE skilled in circuit analysis who's been working on the circuit for 20 years would has already figured all of this out.
You need to go directly back to the excellent advice already posted:
I really should have flagged this hobbyist or homeowners post when I first saw it even though other valued forum members had already responded.
RE: power spike removal
I see no indication of any tripping or reset components on the device labled "Reset Switch".
Is it the high limit that is tripping? It is generally the high limit that has a reset button.
That would be either the high limit calibration is off.
Or re-closer events are causing a combustion problem.
Normally when the thermostat is satisfied the burner shuts off and the fan keeps running to cool the heat exchanger.
Compared to all other burners that I have worked on:
The Fan Switch should be labelled "Lower Limit".
The Lower Limit should be labelled "Upper Limit".
The Upper Limit Should be labelled "High Limit Trip".
Typical operation:
1> Burner starts.
2> When the heat exchanger is up to temperature, the Lower Limit starts the fan.
3> If the heat exchanger gets too hot, the upper limit shuts down the burner until the temperature drops and then restarts the burner.
4> When the thermostat is satisfied, the burner stops and the fan keeps running to cool the heat exchanger The Lower Limit cycles the fan off when the heat exchanger is sufficiently cooled.
5> If for any reason, generally a failure of a component, the temperature of the heat exchanger keeps rising, the High Limit Trip shuts down the furnace and waits for manual intervention.
A re-closer event may be interfering with the normal shut down cycle and somehow causing the heat exchanger temperature to rise past the set point of the safety limit.
Have you checked your air filters? Dirty filters may cause higher than normal heat exchanger temperatures. If this is the case, it would take less of an operating cycle abnormality to trip the high limit safety.
A surge suppressor similar to the one that I suggested will probably avoid short cycle issues overheating the heat exchanger.
And you will be vindicated. You suspected a surge problem and installed a surge suppressor and the problem was solved.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
The upper limit protection is likely one of those 2 terminal metal case click switches that resets itself.
RE: power spike removal
In addition to the upset cycle issue, there may be a case where there is not enough voltage properly run the "Gun" burner, and so the flame doesn't light.
Alternately, there may not be enough voltage to initiate the ignition spark.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
I think that the main problem is that of communication. When OP says "spike" he probably means any main anomaly. For most of us, a spike is a short duration overvoltage - like an inductive kickback or some other short-lived phenomenon. So a spike is usuallly something like a 200 - 500 peak with a width that can be anything from tens of microseconds to one or two milliseconds.
Such a disturbance cannot be observed with the eye. Impossible.
Next, if you look at the diagram, the triac, flame detector and relay are completely and galvanically separated from the grid and fed from the 24 V secondary of the "TRANS" which is NOT the ignition transformer.
To make the influence of a spike even less probable, there are Three Components forming a low-pass filter in series with the triac and diac. The latter also has an RC Circuit that defines the gating angle and makes the sensitivity to external spikes extremely low. An unvoluntary triggering of the triac does not stop the burner. So one can forget about spikes altogether.
A transient voltage suppressor will not help at all. There are a few other recommendations in this thread. Please consider them, but I doubt the PipeMan gadget very much. It sounds very much like the "SineTamer" which is also a hoax. Like my Nuclear Filter was.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: power spike removal
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
The device you posted Bill could work if it reacts quickly enough to the power transients.
RE: power spike removal
The protection device works by keeping the circuit off-line for three minutes to avoid whatever line conditions are causing the problem. If the lights are flickering, then quite possibly the furnace is trying unsuccessfully to light. Each try adds heat to the trip heater because the flame never does light.
If the voltage is too low to generate an ignition spark, then the flame detector will trip.
To expand on Gunnar's suggestions; Transients generally have very steep wave fronts. Essentially the first half cycle of a very high frequency. This high frequency is easily blocked by the impedance of transformers.
Even if a "Surge was to trigger the triac it would turn off at the next zero crossing.
With 60 Hz there is a zero crossing each 8.3 milliseconds. If a surge does trigger the triac, it will shut itself off in about 8 milliseconds or less.
Are we to accept a series of surges at the correct time to be most effective every 8.3 milliseconds?
Consider 4 or 5 failed restart attempts in 20 or 30 seconds. That can easily happen on a rural distribution line.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
The design of the flame detection circuit makes it rather immune to spikes. As Gunner pointed out, there is filtering on the circuit. As I pointed out, the triac would go off again in 1/2 cycle if it was triggered on by noise, which is way too short a time to cause a trip.
As you pointed out, you've got to know what the problem actually is before you can create a solution.
I should have probably asked, because details on that vaguely described delay timer protection would have been nice. The coil on some delay timers can cause the timer to hold-in until the voltage drops quite low. Much lower then you would want to use as an under-voltage trip level for a circuit like this. So, that timer circuit that is supposed to be protecting against low voltages might not be doing anything very useful.
RE: power spike removal
The device trips off above 140 Volts and below 90 Volts.
This may not help with transients but it sure works on most of the low voltage problems that are erroneously blamed on transients.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
The oil burner control should take about 30-45 seconds to trip without a flame. The thing is rather dumb, there is not sequence of operation. Basically, it just calls for the oil pump and ignitor to be on the whole time the thermostat is calling. So, the question should not be how to stop it from tripping when I saw a short power line disturbance, but rather why does it trip when there is a short power line disturbance. 30 seconds of brown-out is rather different than seeing the lights flicker once or twice.
RE: power spike removal
Now I undertand what you meant.
I have had issues with rural lines at different times and in different places.
A fairly common pattern for a tree failing across a rural line is a trip of the recloser and a dead line for a few cycles or a few seconds.
Then the recloser closes in. If the fault is still there it trips out again.
After a short time is closes again.
I have seen reclosers set to close in as many as five times before tripping off permanently.
I fortunate enough to see a tree fall across a line. The line didn't trip immediately.
The current started to track along the tree trunk. A bright pink line was seen on the tree trunk as the current built a breakdown path. It took several seconds. Then there was a flash and a bang and the recloser cut the power. A few seconds later the recloser closed and the pink line was seen again. Several seconds to trip.
This was repeated five times before the recloser cleared the line permanently.
I imagine that other lines fed from the same small rural sub would experience fluctuating low voltage.
Anyone between the sub and the fault would see the lights dimming and flickering.
I can see such an event being described as flickering lights on unfaulted lines from the same sub.
I theorise that voltage is too low for the ignition transformer even if the burner motor trys to run. However if the low voltage is enough to trigger the protection circuit for enough seconds it could trip off.
I understood the OP that the circuit trips in about 15 seconds.
Using the protector will also avoid the possibility that the burner motor is running and delivering fuel to the fire box that is accumulating rather than being ignited and burned properly.
Small amounts of unburned fuel, yes, but something that it may be well to avoid.
The OPs timer may well work, depending on the cutout voltage.
My point is that there is probably no spike or surge or transient.
The most likely issues is power drops and brownouts over a period of 20 to 40 seconds.
The solution is to stay off line until the power stabilizes.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
RE: power spike removal
I probably meant 5 trips and 4 reclosures.
Thanks for the clarification.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: power spike removal
RE: power spike removal
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: power spike removal
A three minute time delay on turn on shall cover a multitude of sins.
Bill
--------------------
"Why not the best?"
Jimmy Carter