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Installing a new generator?

S

spinjector

Hi all,

I just took the wheel for a cluster that needs generators installed at two transmitter sites. I've never done this before, but to me it seems pretty straightforward: find contractors, choose brand/size, get estimates, wait for the bean counters to do their dance, and then get the work done.

Have any of you done this before? Any suggestions? Questions to ask and things to watch out for?

Thanks.
 
If your fuel will be propane, you will need to consider the ambient temperature(s) and tanks size; especially if your new genset will only burn vapor.
 
How accessible are the sites? I worked at a back up data storage center (downtown Atlanta) that used natural gas. If you are in earthquake prone area, on site fuel is best. Also contact your local Emergency Management Service. Most counties have one. Sometimes they will "fund" your generator. Especially if they use EAS for Tornado / severe weather emergencies, Mattie and or Adams calls and or announcements.
 
We have a site that only needed a small generator--2500 watt transmitter plus tower lights--total load around 8 kw. So I bought a 11 kw Onan.

Big mistake. Little two cylinder Honda tiller motor--impossible to find anyone to fix for a reasonable price. (Local Onan repair is NOT reasonable.) On the other hand, the 20 kw we have at the studio--another Onan--uses a conventional GMC truck engine. Local Ford dealer can handle servicing.

So if you only have a small load--don't get anything smaller than a 20 kw. Will save you money in the long run.
 
Biggest probelm might be local government. Get all the details first, permits expecially fire permits can be killers. Make sure there are no noise rextirctions if it's a populated area. We've been having a delay in accepting our new generator for over 6 months now because one of the walls around it is a foot to short. Luckily we have been able to use it "temporarily" while waiting for the FD and contractor to agree on the solution.
Bill
 
See this is why it's good to ask what I should ask. ;D

TomZ said:
...you will need to consider the ambient temperature(s) and tanks size; especially if your new genset will only burn vapor.
Click to expand...

How should temperature be considered? Is the concern too hot or too cold? Both of these sites are in the southern Adirondack region of NY state, and could be subject to winter nighttime lows of minus-40 degrees or lower.

Two of our existing sites already have propane, and it appears to be "gas", as the tank & connection resemble those of a residential installation. Ie- the HP regulator is on the top of the tank, and the gas is supplied via plain copper tubing.
 
secondchoice said:
How accessible are the sites?
Click to expand...

After the Hurricane Irene disaster, I can assure you the new generators will be utility-independent.

And thanks for the suggestion of government funding. I will definitely look into that..!!
 
I have used mostly cummins/onan stuff and had good luck although there factory service is overpriced.
I would just say to be sure you have an accurate idea of your load and to plan for no more than 80% loading. And to be aware that if you choose propane or natural gas that they are best used on smaller power need sites, diesel will allow you to go larger.
As far as your ATS it all depends on what options you want, I have never found the need to use to many advanced options other than closures to know its on and transfered, but there are units now that have html pages and all kinds of stuff.
 
@ spinjector, I can't quote the exacts until I re-read; but my memory from reading the winco manual for their 20kW genset (4 cyl. FoMoCo) suggested a 1000 gallon tank in order to provide enough evaporation surface to run this unit at full output when the tank temperature was ~10 below zero F

Liquid propane isn't a problem; but your unit must be built for liquid. This winco wasn't field convertible.
 
And thanks for the suggestions on engine size, kw, & parts availability. Two of the sets we have are 5.7L Chevy engines, so yea those are easy, I had a '76 Cutlass with a 350 in it. =-)
 
TomZ said:
... in order to provide enough evaporation surface to run this unit at full output when the tank temperature was ~10 below zero F. Liquid propane isn't a problem; but your unit must be built for liquid.
Click to expand...

I understand about the surface area. The set at our big stick has a tank that's about 12' x 3'.

When you say the unit must be built for liquid, could you explain that a bit more? I'm assuming the tank, HP reg, lines, LP reg, carb, and engine tuning all have to be built for it yes?
 
Coming late to this discussion so please forgive if anything here is redundant.

What's your real need? That is, do you intend to tun full power while on generator? If so, how much power? What else is at the site?

My experience is with installations intended to run at -50 degrees F. Diesel powered. For the 25-kW site I run a 3-phase 480V Northern Lights/John Deere rated for 66kW with no special provisions (more below). In addition to the transmitter load there are, of course, tower lights, all the peripherals and a 1-kW NOAA transmitter in the load. Under full modulation the poor thing works hard but has been up to the work. If there were any computers out there it would be a pig of a different odor...more about that coming below.

I would never mess with propane in a cold environment. The evaporation factor is critical as others have explained but propane does not pack the available power of diesel fuel. But diesel will congeal at low temperatures so it's important the gen set be in a heated building with a nice warm day tank; no cooler than about 50-F. The fuel outside will get thick so the feed to the day tank pump oughta be at least 1-1/2 inch; preferably flex hose (where I am the building and tank shift vertically with the seasons).

At the studio site I run the same basic unit but configured for single-phase, 55-kW. Now the measured load is less than 12-kW. The reason for over-sizing is advice from APC who makes the UPS units in the studio. They tell me stated power draw on computers is an average but the switching power supplies have spiky peak requirements so they recommend generator capacity THREE TIMES greater than the measured load. Without that when peaks coincide the waveform from the generator degenerates and the UPS units will reject it and jump back to battery. The cycle repeats over and over until the UPS batteries are dead.

OK, so that suggested a 36 kVA generator but that leaves no headroom. Next size up, which provides very nice headroom, was 55 kVA at the time and the price difference was about 8%. Additionally, APC suggested we specify permanent magnet excitation plus precision voltage and frequency control. Those features added a few more bucks but the unit has been running over 15 years (not a whole lot each year) without strain. But it IS important that you exercise your generators at least a couple of times a month and pay attention to them while they're test-running....else when you need them they won't work.

For diesel, most places now demand double-bottom tanks in case of leakage but remember, leaked diesel fuel will burn if you work hard enough at it. Propane, OTOH, will explode.

Only reason to go cheap on a generator is if the owners plan to sell within a year.
 
It is interesting to read the replies about using propane to drive your gensets.

Here in New Zealand, diesel is the order of the day. It stores well, it doesn't have special DG requirements, it is easy to transport and the cost is reasonable given the generators rarely run.
Most sites use Caterpillar or Cummins diesels driving 30, 50 or 100 kW alternator heads.
For sites in cold locations, the cooling systems of the engines are kept warm with a heating element that will kick in when the temperature drops below 10 °C.
All systems are full auto-start/auto-shutdown with supervisory.

In terms of supply and install, you are on the mark.

1) Determine peak load.
2) Multiply by 5
3) Get prices for supply and install of the equipment including all electrics, genset controls and fuel storage/delivery systems.
4) Submit to beancounters.
5) Wait for shouting, bad language and flames in accounts office to subside.
 
When studio 1 brought up "accountants" gave me another thought. If the local government can't fund you, check and see if there are any emergency power "dealers" in your listening area. I know of an operator that "traded out" and basically got their stuff "free". It has been done with cars and station vans for years.
 
Discuss the diesel fuel and low temperature. Had a gen set we ran heaters on the block. We used a fuel additive from the coop to keep it from gelling but had no special heating of the tank. It handled Indiana winters well.

Got tired of cycling and causing the load to switch on the Cummins set. Found it had a provision to run without load switch and was programmable. (Not eprom but an old rotating timer) Thi feature of running independent of load switch is great.

The cost of a trade for generator could exceed buying it outright. A station did a trade on a BMW and by the time tax on the trade was considered the car would have been cheaper if purchased outright. Any time I see a trade and am told there is no expense it never considers the taxation of the trade. Many times the trade is valued at a higher price to allow for more station airtime.
 
One more thing I should mention.

Make sure you include a time delay on the mains fail relay on the main switchboard.

I had an incident some years ago where I was called out to a tx site due to 'very strange readings' coming back from
the supervisory system.
It was a wild stormy night, raining and cold. Not a nice night to have to go out!

Anyway, when I got there, I went into the main transmission room and the fluoro lights were flashing on and off, the transmitters were going nuts, meters flicking up and down and contactors on the distribution board dropping in and out.
The generator was running.
First thing I did was throw the main switch off - to force everything onto the generator supply.
Once I did that everything settled down, and I was able to look at what was happening.

The site was fed from a three phase overhead which came up the side of the hill.

As it turned out, the wild weather has caused a connection on one of the lines to loosen, and every time the voltage dropped off, the system would switch over to the generator supply.
The voltage would return, and instantly switch the system back to mains, and so on.

As you can imagine, not ideal - and it produced the symptoms I described.
The solution was to fit a time delay to the mains fail relay, so that normal mains service needed to have returned for at least 30 seconds before it would switch back.
 
similar wild and stormy night type story, the room was going nuts, but the generator had not come on! Turns out the neutral had opened intermittently on the pole, the equipment in the room was not a balanced load and the generator sensor was only on the side that usually went high. Rigged a relay so that either side going low would trigger the generator and switch. Half the room was two way stuff, the other half a 25 KW FM transmitter. the lights, and rack were going nuts as was the two way stuff. Lucked out and nothing suffered serious damage.
 
I was testing a new plant's 150KW Cat genset, running a Continental 50KW FM system and ancillary equipment. We'd set the radios up with the phase loss relays 'riding the peak', about .5 above dropout. So. On comes the genset. The transmitters ramp up to power and the waveform garbaged enough to trip out the pahse loss. Until the load came off the set and it cleaned up. At which point it turned them back on. You can make a Cat 3208 engine jump about a foot every half second if you do this just right. Horrified the Cat tech, fortunately didn't hurt anything, and we reset the pahse loss relays back about ten degrees on the setting pot.
 
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