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Generator or Backup Options?

Generator or Backup Options?

Generator or Backup Options?

(OP)
I have what could be a quite basic question for you electrical guru's. I have some equipment that is in a rural area. During the storm seasons, intermittent power outages can occur. This causes the equipment to shut down, and must be manually turned back on.

My first thought was to get a generator to provide as a backup. But if I had some form of a battery backup, this may suffice since the outages are brief (a few seconds?). The power requirements are 45.6 amps.

What would guys recommend from your expertise?

RE: Generator or Backup Options?

(OP)
I assume this equipment can't get wet? I'm not sure if it's applicable to field conditions, and may apply more to computer equipment.

Maybe I can set something like this up in some sort of a meter house. Any additional thoughts?

I forgot to mention its 12 HP @ 45.6 amps, which includes surge for starting.

RE: Generator or Backup Options?

12HP will be one expensive UPS.

Can you give us details on this equipment?

What's the various equipment consist of?

What exactly does the poor schmuck who has to drive out there do when restarting the system?

Is this motor 3phase?

There could be some alternatives to the brute force method of a UPS.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Generator or Backup Options?

(OP)
That's the core of my question. What are my options in your levels of electrical expertise? Use a natural gas powered electric generator? Is there a form of battery backup available out there (that would fit this application)?

The equipment is an amine processing plant. There are 4 total electric motors:

1.) 5 HP - powers pump of fluid to amine tower
2.) 5 HP - powers fan (cooling of fluid return from re-boiler)
3.) 1 HP - booster motor pushes clean amine fluid back into surge tank (supply)
4.) 1 HP - powers reflux pump, condensate from steel column to reboiler.
 

RE: Generator or Backup Options?

You're pretty well into the area where a natural gas powered backup generator would be a good choice.  Auto transfer on utility loss, retransfer on utility restore, and a PLC to do an auto restart after transfer on one direction or the other are also indicated.

Battery backup is going to be pretty expensive in terms of  the load, just to get a short time of ride-through, and as you look for longer periods on the backup system, the battery bank size is going to be BIG.
 

old field guy

RE: Generator or Backup Options?

(OP)
Ok thanks for the info. Your answer leads me to a few questions:

What is a PLC, and typically what size of generator would be required to provide the power requirements? Is there a good website or rule of thumb to go by?

RE: Generator or Backup Options?

Thanks for that info.

Here is my point.  If you can just pull the plug on your system and it fails/stops "safe" and an hour or a day won't hurt anything then you don't want the hassle of back up at all.  You just need a way to restart things.

A generator is a theft target.
Now fuel is a target too.

It needs;
1) A thought out installation
2) regular testing
3) on site fuel storage
4) Permitting (sometimes)
5) it's own battery
6) regular servicing
7) Then you still need a way to restart things as the generator is not going to spring to life in less than a 1/4 second.

I suggest that if your system just needs a bunch of buttons pushed to restart everything than power-on timers set to start things in the normal sequence with appropriate delays would be the logical solution.

If however you need things to start in a certain order AND each thing must be working a certain way before you restart the next item (some do).  Then you want to use a Smart Relay(cheap PLC) or a PLC to start things in the sequence desired and to check for conditions of interest before starting the next process.

DEF:  PLC = Programmable Logic Controller.
It is a small computer system that is designed for industrial applications.  It generally has a wider operating range than a PC and is somewhat hardened, and has industrial mounting, and field connections.  They need programming to do what you want.  Your application would probably be very easy to program.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Generator or Backup Options?

(OP)
Hey thanks for the replies.

This is a natural gas compression site. We can utilize the natural gas to power any generators.

The amine facility removes H2S, CO2 and other contaminants from the gas stream. It is important to keep this running. The agressive storm season has brought a touch of inconsistency with the electric. I feel a backup is needed for sure in case electric may go down for X days. It seems to be sensitive to any fluctuations that may occur.

Perhaps a mix between the recommendations. A PLC + natural gas driven generator inside a protected building? A battery solution has seemingly been eliminated due to the power requirements and cost effectiveness.

The equipment is already installed and is inspected everyday. The on site fuel could be the natural gas.  

RE: Generator or Backup Options?

Quote:

But if I had some form of a battery backup, this may suffice since the outages are brief (a few seconds?). The power requirements are 45.6 amps.
If the system can survive until someone drives out to restart it, it should be suitable for an auto-restart.
I agree with itsmoked.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Generator or Backup Options?

Any possibility of running a small generator off the turbine that's running the gas compressor? (Assuming that the compressor is driven by a gas fired turbine.)  That way could always feed the critical load from the compressor system then you could be immune from utility problems, but could use the utility as a back up source when the compressor is down.

RE: Generator or Backup Options?

Barring davidbeach's idea being a good fit, then a gas fired generator, an automatic transfer switch, and a smart relay to run everything sounds like the ticket.

OK Size..

waross; What are the numbers?

Quote:

The equipment is an amine processing plant. There are 4 total electric motors:

1.) 5 HP - powers pump of fluid to amine tower
2.) 5 HP - powers fan (cooling of fluid return from re-boiler)
3.) 1 HP - booster motor pushes clean amine fluid back into surge tank (supply)
4.) 1 HP - powers reflux pump, condensate from steel column to reboiler.

15~18kW?

You'll want to package up the smart relay and any required transfer switch controls, etc. Into a NEMA 4 enclosure.  Etc.etc.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Generator or Backup Options?

(OP)
Thanks for all of the discussion. Unfortunately connecting to the natural gas compressor would not be an option.

I believe I've got a pretty good starting point now to evaluate the options available. If the thread remains open, I'll try to post back what the final setup turns out to be.  

RE: Generator or Backup Options?

15~18kW should handle a staggered start. For a simultaneous start you would want about 25 kW. (assuming 0.8 power factor)
I would be wary of possible fast transfers.
The safest and simplest way is to delay the start of the restart cycle for 15 or 20 seconds.
 

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Generator or Backup Options?

(OP)
I figured we could stagger start each motor with about a 15 or 20 second delay like you mention by using the PLC.

Im researching generators... It looks like some come with transfer switches, but they're manual type. Hopefully a portable size generator will work. I don't know if you can post links, but I found a Guardian 5396 Centurion 17,500 watt electric start portable generator that looks like it may work. Seems to be about as big as the portables get.

RE: Generator or Backup Options?

I'm not sure you want a portable generator -- remember that they can walk away!  If the generator is intended for this site, then fix it in place.  By the time someone arrives with the portable generator, I suspect your outage will be over.

Any idea how often and how long power outages happen?  Also, I was wondering about the comment you made about sensitivity -- do you run into problems with brownouts or voltage sags?

RE: Generator or Backup Options?

(OP)
Yea I was thinking portable in size and would mount it down. This would be installed on site with a PLC and automatic transfer switch. We could probably use the PLC to delay the auto transfer back to primary as well so the generator doesn't just have to run for 5 minutes. Maybe let the backup run for at least an hour before transfering back.

As far as sensitivity, if any lightning strikes occur in the area or anything, the system shut's down. The potential exists for a complete outage for a few hours. It's important for the system to stay running, so I don't want to assume power will just flicker and be back to normal. I want to plan for the worst and hope for the best. If power does go out for several hours, or longer I need to have the proper equipment in place.
 

RE: Generator or Backup Options?

You could always invest in some automatic motor wound 3 phase breakers - you can then configure the PLC to operate those circuit breakers depending upon the mains status. you would need to use a phase fail relay to monitor the line and have this operate the ACB's. The PLC would then need to run up your equipment in the correct sequence. Functionality would need to include if you had a power outage during the sequence and things like that. Ensure that your run up process would run up what ever happens.

Mains fails - 10 second delay starts swap over proceedure all kits requiring sequencing is dropped. The ACB incomer opens. Signal sent to generator this startsup and makes the generator phase relay happy. This times out and thens end a close signal to the generator incomer. The supply is not live to the board and your kit can go through a start up sequence. Do you need a hold off time so that if the mains came back on within say 5 minutes you would hold to generator or would you like to throw back over right away. Again think out the process for swapping back. Scheduled switch down of plant change over to utility and then sequence back up to normal operations again.

What you are talking about is quite a difficult process to think and apply some logic to - you need to eb 100% sure of your requirements and then make up a schedule of switching required and work from that. Think about how long you want to run on generators if you have switched over - put a delay in to stop say rapid back and forths if you dio have to go to generator - stops rapid drops in supply having your system fluctuate.

RE: Generator or Backup Options?

allsyntax-

Recently I've been reviewing some replacement packages for backup generators here.

Most of them have control packages that take care of making sure that the generator doesn't "run for 5 minutes".  If the generator doesn't have it, then many transfer switches have that feature in their controllers.  One or the other will likely also include a periodic start and run of the generator so you can exercise it.

There are amazing capabilities in the new equipment, to the point that I sit here scratching my head wondering if we're getting a bit TOO complex for a simple generator backup scheme.

  

old field guy

RE: Generator or Backup Options?

(OP)
Thanks again for everyones comments.

I dont have a background with electrical details, so thats why I thought I would talk to you guys for your expertise on the subject.

Ideally, you would want to keep the setup as simple as possible. I did see where some generators have packages w/ transfer switches, but I didn't see any that were automatic.

I think the trick of complexity lies in the kW required for startup. I have 4 different motors, so I believe thats where a PLC may come into place, opposed to just having a backup generator w/ transfer switch.

ruggedscot is right, that this should be well planned out in regards to the timing. ruggedscot: You sort of lost me in your first paragraph.  

RE: Generator or Backup Options?

rugged,

ACBs? For a 45 amp load? You must have money to burn. smile

  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Generator or Backup Options?

If you want real reliability then add a test load and have the PLC run it once a week and leave a green light ON if the load was run successfully or a red light if not.  Then who ever visits just checks the light.  If it's red then investigate.  You can also have to PLC flash the red light if the generator needs it's annual service.

The PLC can have the generator run the test load for 15 minutes a week so you dry out all the accumulated moisture from the engine oil etc.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Generator or Backup Options?

(OP)
Ok thanks, great links guys I will be looking into those.

Im trying to go over the generator requirements based on the data I have.

So if watts = (amps * volts) * load factor

Then, I would be at (45.6 * 240) * .8 = 8.755 kW

Is this correct? Would that for general operating? And I would need something in the range of 15-18 kW due to motor starting power demand? Can you guys educate me in this area?

 

RE: Generator or Backup Options?

Yes motors require much more to start successfully then just their running load wattage.

As for your 45.6A that really means nothing in the context of how you've been using it.   Have not a clue...

Is this three phase power or single phase power?  Where did you get this number?

When it comes to motors, you are interested more in the HP than the current when sizing generators.  You back into the current from the horsepower requirements.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Generator or Backup Options?

allsyntax:

Joining the party late, but you need to define the problem and the goal first. The original post suggests "This causes the equipment to shut down, and must be manually turned back on."

Is the issue shut down of equipment or just manually starting back or both?

If just manual re-start is the problem, generator will not help as the equipment still will shut down and needs to be started up, either automatcially or manually.

If only a auto-start will solve the concern than all you need is auto restarting control circuit, which is pretty easy.

If even having momentary shutdown is an issue and you do not want to go down at all than you wil need a UPS. If the outages are longer than a few minutes than you may need both the UPS and generator. YOu need to define your issue further and apply the appropriate solution. Hire some experienced professional help.


 

RE: Generator or Backup Options?

(OP)
Yes, we have covered all of that.

In my last post I just wanted to see if I could calculate on my own how many watts would be required to operate the equipment to size the generator.

It's single phase electric. One of our operators gave me the 45.6 number. He may have totaled the # from the badge of each motor, I'll have to check back with him to see exactly.

Also FYI I will not be installing this myself. I'm just researching what options were available and I thought who better to ask than electrical engineers, no harm no foul :)

RE: Generator or Backup Options?

The major manufacturers offer enclosed packaged sets and automatic transfer switches. The packages are enclosed, weather proof, and quiet. The best pricing that I have seen for automatic transfer switches is when they are bought as part of a generator package. F.G. Wilson,or Olympian (CAT owned) Onan, and others.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Generator or Backup Options?

Most of the manufacturers also offer sizing software that you can use or that they will use for you.  Put in your loads, your voltage dip criteria, the starting sequence, and out comes a generator size that will meet those criteria.

RE: Generator or Backup Options?

(OP)
Ok thanks. I will be looking into that and let everyone know what was ultimately decided.  

RE: Generator or Backup Options?

A tip on comparing generator offerings from various vendors.
18 kW to 24 kW is about the maximum size of single phase generators. Above that size three phase alternators are reconnected and re-rated for single phase.
You may be faced with sales proposals for both single phase machines and re-connected three phase machines.
For example, a three phase 30 KVA, 24 kW, 0.8 PF alternator will be reconnected as a single phase, 20 KVA, 20 kW, unity PF machine. The engine will still be capable of producing 24 kW. although the alternator will be overloaded.
A single phase 20 KVA machine will have an engine suitable for 16 kW or 20 kW depending on the power factor rating.
The re-connected three phase machine will start motors much better than the single phase machine. The short overload on the alternator during motor starting will not be an issue. The re-connected three phase machine will be well worth the extra money that it will probably cost. The engine will last much longer also.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Generator or Backup Options?

This sounsd like a perfect application for fuel cell technology. The company I work for has done several pilot plant studies using different types of fuel cells, not just conventional Hydrogen powered. e.g. Liquid/Liquid for power station Black Start and Submarine.
Since you have natural gas available a Hydrogen/Air fuel cell would be practical.
Regards
Roy

RE: Generator or Backup Options?

I was just reading this and thinking what Roy has posted. Some sort of continuous operated generator could be practical and forget using the hydro company supplied power completely. The last time I was in an oil/gas area I saw a few generators that were running fuel cells or some other technology.


 

RE: Generator or Backup Options?

(OP)
Thats very interesting. A lot of helpful information provided by everyone. I will have to look into this option as well. I realize this thread has become quite lengthy (which is a good thing), so thank you for those who continue to take the time to read through the discussions and provide input based on your experiences.

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