Generator Engine Control

After a while you learn to just look and listen for a while and the clues just start talking to you.

Asking the right questions in a non technical way I find is the biggest trick Philip. I have a bad tendancy to rattle off in technical terms at a milion miles an hour and most people do not have a clue what I am talking about.

Also have a bad habit of half saying something and the mind is already a million miles away. I know what I meant but the half information totally confuses everyone else. Those who know me say "WHOA". Go back a few miles and explain.
 
I'm new to this field. The company I worked for makes panels for controlling backup generators, and mainly power distribution for high/low voltage supply. I first started out drafting layouts and writing manuals. Then I went on to do PLC programming, building up panels and wiring and testing. Most of the projects I done (countable by hands) are with diesel engine generators. So far, they are all controlled by PLCs.
But I went through some older projects dated about 10-14 years ago, and found some pretty interesting panels which controls a diesel genset without the use of PLC. I am confused as the drawings are very messy (full of wirings and small components), not understanding most of the context. :oops:
I'm terrible at testing till now...Sometimes not figuring out where the problem is coming from, and drag precious time. Other times, I have a hard time browsing through the drawings and not knowing what to do to get it started. So I irritate my senior a lot with every little bit of problem. I feel so terrible about it sometimes.
I'm still struggling to learn so I hope I can do better in due course. :)

Regards
Sherine T.
 
Drawings

Sherine

Stop and think a moment on how many times you see people saying here
DO THOSE COMMENTS
LABEL those switches
SAVE COPIES

All this is done for THE NEXT GUY. THE NEXT GUY may be you in two years and YOU WILL say now what did I do?? How did I do this??

Let me tell you if you have poor drawings or inaccurate drawings it i like being in a strange town with no map.

Sometimes it is better to throw them away and make your own drawings - generaly irritates a boss who does not do troubleshooting or has forgotten reality.

THen they get all ticked off because it takes only 15 minutes or so to replace the relay fuse whatever AFTER 4 hours (4 days ??) of tracing.

THE END POINT
UNLESS you work on the same identical piece of equipment time after time you MUST have good drawings to do the job quickly.

Every different piece of equipment is a new learning curve.

THere is no need to feel bad.

Dan Bentler
 
MORE DETAIL ??

Bob B

In previous message you said:
SCADA systems are nearly always used over the top of complex systems. I always put an "automatic return" button on the control cubicle in case Mr Gates operating system does what it does best. That way they can put the building, or whatever, back to normal without the computer.

I have inherant mistrust of turning over all control to computer. Some of that comes from submarine service where we ALWAYS had local manual override. Another comes from Wa state ferries crashing into dock because of computer failure AND lack of operator on override switch. Further added to by experience at Trojan Nuclear Plant and Experience Music Project (Seattle) where computer controls were fine as long as up and running BUT try a a cold plant start or restart after power loss.

SO curious and would like a little more on statements
I always put an "automatic return" button on the control cubicle

IS this similar to my desire for manual controls /overrides on PLC controlled genset???

Dan Bentler
 
I did a large prison job several years ago, with lots of remote monitoring and load shedding where the "heart" of the system was a 9030, with a backup 9030 for other critical operations, and the PC with cimplicity was for remote monitoring and control, not the "brains" of the system. But the engine was still controlled by 7 relays (well, actually 25-30) and a timer.

I didn't trust a PC or Cimplicity. In fact, I wanted the generator to start if the PLC quit, so I stuck with the tried and true technology. Even though, relay socket failure ran rampart and cuased many gensets not to start, and more not to stop.

So, going to try PLC's on diesel engine powered equipment. First PLC cranking panel I attempt will involve an Entertron unit. At one time, one employer was cranking out a 50-100 standard cranking panels a week, not counting the specials. The entertron's should be well suited for this tye of application. The heavy duty outputs should be more then adequet, and I will probably slave a solenoid for the starter, at least initially, just to be safe. I realy looking forward to it.

regards.....casey
 
SO curious and would like a little more on statements
I always put an "automatic return" button on the control cubicle

IS this similar to my desire for manual controls /overrides on PLC controlled genset???

No Dan. Very definately not.

The auto return button is an input into the PLC. It only bypasses Mr Gates monster where the return to normal power is instigated either collectively or 1 point (floor) at a time from the SCADA system, if the computer fails, or locks up.

In 12 years of doing generation work I have only had 1 24VDC power supply failure with Omron PLCs. Add to that 2 year warranty on ALL Omron products in Australia, I have no reason to use anything else. Have had several problems including power supply failure, processor failure, processor lock up, remote communications failure etc with other brands from Japan, US and Europe. No names mentioned, I have no intention of starting WWIII.

I believe in operating ALL my generator system designs through PLCs. In fact, I do not know of any other economic way to control 90 odd switch boards in a building, all with their own power failure relays, and spread over 50 odd floors without using a reliable, networked PLC system.

How would one accomplish load control, capacity control, automatic load bank control to keep the sets loaded above 50%, without a PLC, etc etc. I would suggest one would be wiring timers, relays etc for 6 months and running cables all over the building, at enormous cost for tradesmen, for another 6 months. Another 6 months to debug the system and commission it. Timers, lots of relays, heaps of drawings, maintenance nightmare. NOT ON!!!!

At the end of the day you always have many single points of failure. A relay, a mag pick up to the generator controller, a load sharing unit, a relay, a power failure relay, etc etc. Timers are notorious. I would suggest that PLCs, generally, are far more reliable than many other components in the system.

I would suggest to you that the Navy are antiquated and out of date with most of their systems. However, I have no problem with having a PLC bypass starting system in case of PLC failure, and implement this in all designs somewhere along the way. One can start the generator manually, and close circuit breakers the same way, as an emergency procedure.

Just about all generator sets these days come with electronic governers (no more sticking racks), load sharing units etc etc. Included are Cummins, Caterpillar, MTU (Mercedes), and most others. They have had to move this way due to anti pollution laws in most countries. How do you get past that to start a set in manual? My experience is that a reliable PLC is more reliable than the generator controls built in by the manufacturer. And do you remember the illustrious Woodward UG8 governors and others of the same vintage? The speeder motors used to slip (and still do), they used to leak oil and fail, sending sets into over speed or under speed, needed stripping and servicing every 3 years whether they had been used regularly or not.

I would suggest to you that a PLC presents far less problems than a lot of other electronic and electro mechanical devices in the system.

On the other hand, I would not trust a PC for controlling any critical system. That is why the auto return button as a PLC input.

Even though, relay socket failure ran rampart and cuased many gensets not to start, and more not to stop.
I think that statement says it all!!! Defeats the purpose of the following line of thinking!!!

I didn't trust a PC or Cimplicity. In fact, I wanted the generator to start if the PLC quit, so I stuck with the tried and true technology.
The entertron's should be well suited for this tye of application. The heavy duty outputs should be more then adequet, and I will probably slave a solenoid for the starter, at least initially, just to be safe.
Better to use transistor outputs to drive diode protected external relays. Much easier to plug in a new relay in the middle of the night than try and find a PLC output card, or solder a new relay into the card and burn off a track because you cannot see. The transistor outputs can be driven equally safely into bi-directional diode protected multi chip super bright LEDs for indication.

Also bear in mind these systems are invariably operating on 24VDC. Relays have a tendancy to finish up with badly burned contacts on DC. External relays generally are larger physically and, therefore, have bigger air gaps to quench the DC arc. I NEVER USE INTERNAL PLC RELAYS TO DRIVE DC!!!!! Rarely even have a relay failure these days using this method. Use Omron G2R type relays. Extremely reliable. They are also available re-badged Allen Bradley if you have trouble getting Omron.

Designed and implemented a base load 11kV generation power station in '96/'97. The system is working constantly, as you can imagine. Sets starting and stopping (load and capacity control, duty order being changed from the SCADA screen, etc etc. THEY HAVE NOT HAD A RELAY FAILURE SINCE INSTALLATION!!!! THEY HAVE NOT HAD A PLC COMPONENT FAILURE SINCE INSTALLATION EXCEPT 1 ANALOGUE CARD WHERE A TRANSDUCER POWER SUPPLY SHORTED BELTING 240VAC INTO THE CARD!!!!

Show me a timer or electro mechanical device that can boast that sort of reliability. By the way, there are 9 networked PLCs on the site with remote I/O all over the place. In that time there have been battery failures, governor failures, cracked cylinder liners, fuel pump failures, fan motor failures, battery charger failures, mag pick up failures, cables snapped from engine vibration turning the copper conductors work hard, oil leaks, 2 fires from diesel leaks. The PLCs are still going.

If the SCADA running on one of Mr Gates operating systems crashes, the power station continues to operate automatically. If a set fails, or is failing, the PLC system starts another set, closes outgoing high voltage circuit breakers to supply the residents and industry, operates the telephone dialler to summon an operator to a fault in the power station. The only problem is that it is not possible to change engine duty order without the SCADA. However, each set can be turned into manual mode and operated through the PLC. Alarms, load information etc continues to be shown on the touch screen attached to each PLC.

If the PLC system were to collapse, all sets can be turned into "dead in the water" mode and operated from the instruments on the control panels. However, the critical single points of failure remain - governors, relays, timers, mag pick ups etc.

I would suggest that the doom and gloom attitudes towards PLCs expressed here are TOTALLY UNFOUNDED!!!!

I might also add that I implemented a power station for the Royal Australian Air Force in '98/'99. The system is automatic including automatic dummy load control, automatic reactive load control, 11kV underground cables are highly capacitive and drive the power factor in to lead, small sets do not like leading power factor (AVRs mainly). Therefore a reactive load bank is required to control power factor back towards unity. When the Air Force hit site (it is a standby air base), they turn everything to manual. They adjust load sharing, var sharing etc manually. Sets go out on reverse power, under frequency, under voltage, over voltage, etc etc. They forget to open HV breakers before starting and dead bus closing sets and wonder why the stes "bounce" due to the enormous inrush of trying to supply 4 HV underground cable systems that are highly capacitive. šŸ™ƒ There are many more blackouts than when the system is allowed to run automatically under PLC control.

Give me a PLC any day!!!
 
The foriegn market is a lot different then here in the states.

Most hospitals have a transfer switch, and a cranking panel, often not even in the same building. Even larger load shedding systems don't seen to be as big as what I have seen included n some posts.


Some total energy packages (circa 1972) for some of the larger malls, schools, banks, etc didn't seem to be that complex. In fact, the system we put into the world trade center was pretty basic in comparison.

Industry standard is still the little psb28 bulb around here. I tried to promote some Allen Bradley pilot devices in 1999, and was shot down immediately, "the sylvania or dialco assembly and bulb at about $2.50 will do just fine". About the only things we can get away using led's on are annunciator panels, and really low end cranking panels. May look into led's as a replacement for the psb28's.

regards.....casey
 
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Absolutely right ON Bob.

When the Air Force hit site (it is a standby air base), they turn everything to manual. They adjust load sharing, var sharing etc manually. Sets go out on reverse power, under frequency, under voltage, over voltage, etc etc.

Fiddlers are an absolute nightmare. I just spent 22 hours this weekend troubleshooting and reworking aspects of a system because it seemed to have developed behaviour that wasn't there when I installed it.

The two engines are controlled by Woodward EGCP's. These boxes are ok in their place but I prefer PLC logic because it is open and you can see what is happening. Well at one point I was testing my reworked IO and was asserting the "AUTO" mode line on each EGCP. The first one works fine, goes into Auto and awaits the "Run with Load" input.

The other EGCP immediately starts cranking the engine. WTF!!! Some fiddler banghead has gone into the password protected area and set up the Loss of Mains alarms to be active. !@#$... total bollocks and aggravation!!! (And on a fixed price :mad: )

By contrast the PLC is off limits to them and is the absolutely reliable part of the system. Every problem I have ever had with this installation has been related to some external outside of the control system. The most exciting was a large 24v cranking battery that literally exploded under my feet due to a total and utter lack of maintenance, ie almost dry!!!
 
Most hospitals have a transfer switch, and a cranking panel, often not even in the same building.

By law in NZ every hospital has to have a fully synchronisable genset...and it must be run to full load once per week for one hour, and "black start tested" once per six months.

What happens when you are in the middle of brain surgery and the power goes off for several minutes while someone is running around with transfer switches and the same some time later when it is time to restore the mains utility supply?
 
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The two engines are controlled by Woodward EGCP's. These boxes are ok in their place but I prefer PLC logic because it is open and you can see what is happening.

Philip

I prefer to use EGCP2's (won't use the 3's, not properly de-bugged yet), although the latest ones from the States have been awful. We set 2 up in a multi story in Sydney and started reading 100A per phase as soon as the generator ACB closed but there was no load, only the generator board bus bars were connected. The analogue inputs had to be calibrated would you believe. Woodward gear we have used in the last couple of years has had it's problems. Much prefer to use the Brisbane designed and manufactured Si-TEC controllers from Dawson Technologies. The best generator controllers I have ever had the pleasure to work with. About 3-4 times the price of the Woodwards. You only get what you pay for. With either of these brands one can see what is going on by looking at the screen or hooking up a Modbus RTU line into the PLC. All data is in evidence then.

If you have not seen the Si-TEC unit, I can supply a website address where you can contact them and get them to send the latest manuals. They are awesome and are designed to control everything from diesel to gas to turbine etc.

I prefer not to do all the code in the PLC as you completely lose the possibility of starting, synchronising and load sharing sets if the PLC or a DC power supply fail. Also, with the Si-TEC units, there are extensive fault diagnostics built in, analogue outputs to drive meters, extensive PID settings for idle, run no load, run with load, synchronised and on line with mains. You can drive the system manually without the PLC. I can understand where Dan and Casey are coming from here. Unfortunately, many do not trust modern technology, although it is many years old. The funny thing is that the same people trust their data to Bill Gates and suspect hard drives. They do not appear to trust "black boxes".

With the Si-TEC controllers there are also 3 analogue outputs. I normally allocate these to power factor (true RMS), kilowatts and kva, I then feed the 4-20ma signals to meters. Saves heaps on transducers and a lot of hard wiring. All data for the PLC, SCADA and touch screens is then extracted on the Modbus RTU line. Works really well.

In fact, the system we put into the world trade center was pretty basic in comparison.

Casey, I would think that in Australia, and probably the Shaky Isles (New Zealand) that there would have been an awesome high technology system put in place. I am really quite surprised sometimes to see the very high tech gear used in the States and then in the next room absolutely low tech, high maintenance, old fashioned systems. It is commonplace for us to install 8-12 networked PLCs in a high rise to control all switching, load shedding, capacity control etc for generator power and then back to normal power. Soft transfer, co-generation, the lot. LV and HV.

Had one just recently where the UPS for the computer system only had 15 seconds capacity on full load. Start the set after 2 seconds loss of power (normally 10 seconds), close the breaker in a big hurry or the UPS dies. Hope the set starts on the first crank or big trouble. Then soft transfer back to mains. Very common set up in Europe also.

By the way Casey, there are now many sites in Ozz running heat recovery systems. Run the generator at least 90% load, put exhaust through heat exchanger, heat water (in a hospital) or swimming pool water, very energy efficient and economical. These systems have been set up in hospitals, universities, etc etc. We even have sites in mines where the methane is mixed with diesel (9 to 1) and power is generated and put on the grid. One site south of Sydney is running 40 CAT sets this way.
 
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Dan, after pondering over your post I have to say...Good point. (y)
Sometimes it is better to throw them away and make your own drawings - generaly irritates a boss who does not do troubleshooting or has forgotten reality.
Did that once and it was real funny. lolis
It's a simple system with 2 Gens and a Master Control. Boss gotta me to draft out the system including what components to use. The actual developer would have draft up a thick stack of paper. I do not know why, but my whole draft ends up to about 20 plus pages including component listings. I submitted my work and few days later, boss asked me if I was kidding him. :oops: SO I was dropped from that post since to do the setup work.
Just one thing bugs me though, I wasn't briefed on what the clients needs. I do up the program from looking at the schematics. Some are logical (like the U-freq alert, U-volt alert. etc.) But some others can't be determined just by looking at the diagrams alone, ya? You guys would have at least some details to what some of those switchs/signals/control do. I thought a person needs to know what he/she is required to do, and then get doing it. :unsure:
How do you guys come up with the program after knowing what your project is?:confused:

regards
Sherine T.
 
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Read the specification, obtain engine drawings, design the system to the specification on the CAD machine (minimum 4 A4 drawings up to 30 or more A4 drawings), sit the drawings on the desk alongside me and write code.
 
I prefer not to do all the code in the PLC as you completely lose the possibility of starting, synchronising and load sharing sets if the PLC or a DC power supply fail.

Bob I do agree with this sentiment but in this particular installation the presence of TWO mains supplies meant that all of the internal EGCP logic was totally inappropriate and a whole new suit of PLC switching logic was developed to handle the application. Essentially the EGCP should never be used on a split bus multiple mains site, it just doesn't work.

Why did we do this? :rolleyes: long story but if I were to put it in a nutshell, "would you believe that a consultant was involved?"
 
PLC reliability

Bob B.

Got out of Navy in 73. On submarine we did generation switching manually. Course it was not that large a plant (2 2MW turbine generators). Kind of got smile from air force guys who cannot handle power plant. Tripping generators on reverse power etc. Course we ran split plant so if we lost one we still had the other.

After that most up to date electrical I worked on was at Trojan Nuclear plant in 76. Then swithced career fields went into Safety and Industrial Hygiene and switched back to electrical and energy conservation.


Am now catching up with industry and taking class on PLCs. So am a neophyte at this.

I would not trust Microsoft software for safety related control systems. I would not have their stuff intermixed with a control system - it just adds more software to get tangled up in.

I see where some people say do not use PLC on safety related equipment ie two hand controls on punch press for instance. They then say PLC is OK if you use a light screen. I definitely am curious about this and need to learn more on what all the requirements are and what is safe to do with PLCs.

I would like a little more clarification on why you would not use computer to control a system but would use PLC. ASSUME it is designed for purpose and has software designed for purpose and no fancy windows stuff.

My comment on override and complete manual control was intended for hospitals and other REAL life safety operations (not some damn bank or office bldg) where you have qualified and competent operators so that all goes to hell you can always get a diesel up and at least pick up the vital load (ie operating rooms and critical care where lives depend on electricity).

Thanks Dan
 

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