New 22kW Genset Install; Voltage a bit low, compared to Utility system

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amacnabb
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Hello all,

I'm a new member here, but a long-time "generator guy"... More info here: viewtopic.php?p=11695#p11695

I recently completed the installation of a new Generac 22kW Genset (LP-powered), feeding a Siemens "generator ready" utility breaker panel (service entrance panel). This is in a new house (construction finished in July of 2020), and I specified to the builder that the panel be "generator ready", as I fully planned on having a stand-by generator. We're kinda out in the boonies, 20+ miles from "town", and have had multiple outages here, over the last 12-months... including the big "snowpocalypse" outage back in February (75% of TX was without power!). Of course, my new generator was still on back-order [from Generac] then, and arrived just a couple weeks after... :cry:

I'll ask my question first, then explain why I'm asking: Can the output voltage on the Generac unit (model 7042) be increased, from 240 volts, to 250 volts?

Here's why...

Our normal utility-company voltage is rather high here, running very steady at 250 volts (125v each leg-to-neutral). However, the Genset output is running pretty consistently at 240/120v. Normally, this probably wouldn't be an issue, except for...

I am also a Ham radio operator. And while most of my "shack" gear runs on 12v DC (supplied by a couple of 40-amp regulated supply's), or directly on 120/125v AC, my 2000-watt linear amplifier runs directly on the 240 line. Because our "normal" [utility] supply voltage is 250v, I have physically changed the taps in the amp to accommodate the higher line voltage.

All that said, Here's the rub: When on the Genset (with only 240v) the amp is very unhappy being "under-driven", as this causes low cathode/heater voltage, and this actually causes the power tube to "wear" prematurely. Worst case, I may have to re-tap the amplifier's power supply back to 240, and just live with the higher input voltage.

So, again: Is it possible to increase the output voltage on the Genset? I figure this is a "dealer only" setting, but thought I'd throw it out there...

Thanks in advance!
~Alan in West Texas

ON EDIT:
I guess I should also post the "basic" information for the unit:


-> Fuel supply type (NG or LP), size of pipe and length of gas run:
Fuel is LP; supplied from 500 gal. tank via 1" NPS poly-line (underground) to the unit, about 40' run from tank to unit; Line pressure is at 10 psi, regulator at Genset set to 11" wc.

-> Model and Serial number of generator:
Guardian 22kW; Model: G0070422; Serial: 3007585124

-> Problem you're having, what have you done so far to try and resolve the issue:
Output voltage lower than utility voltage (lower than I'd like it). Nothing done yet.

-> Do you have access to testing equipment such as a digital volt meter and fuel pressure gauge:
Yes: Fluke digital meters (true RMS), gas pressure test set (diaphragm gauge manometer).

-> How long has the problem been happening, during cold/warm weather?:
Unit is new, virtually zero (0) run-hours showing on unit. Unit has been run, but apparently not a full hour yet.

-> What has the maintenance been like for the generator (a lot of problems are due to a lack of maintenance):
Unit is new, virtually zero (0) run-hours showing on unit. Unit has been run, but apparently not a full hour yet. Oil and filters are new (factory/original).

Thanks!
~Al in West Texas
Birken Vogt
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There is a spot in the dealer menu to change voltage. I will leave it at that.
amacnabb
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Great, thanks. I kinda figured that was the case...

So, is the dealer menu a "super-secret, no mortal can have access" kinda thing? Is there a unit-specific password, or is it a generic, "all 'authorized dealers' have access" type code?

My local Generac "authorized technician" wants $250 to come out and up the voltage ($125/hr., portal-to-portal). That seems a bit excessive to me, for something that's gonna take like 30-seconds to change.

Thanks for the reply though.
Last edited by amacnabb on Tue May 04, 2021 12:48 pm, edited 1 time in total.
~Al in West Texas
grsthegreat
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You can purchase a diagnostic manual and find access, however mis programming can destroy generator. Personally I would not run 250 thru house, but I can see your reasoning. Very odd that your utility would even allow their service to provide that.
amacnabb
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Well... here's an update to the original question/issue (if anyone cares):

Contacted the utility company (AEP), and they sent out a field tech. He checked and confirmed that my incoming voltage is 250/125, and that their distribution transformer cannot be re-tapped for voltage adjustments. He also said that, in this part of [west] Texas, they always strive to deliver right at 250v, although during summer peak-demand, it may drop slightly (although I did not see any drop last summer, but I know it can happen). The Tech also indicated that they (he) have run into this issue before, with a Genset's output being lower than their normal supplied voltage.

Since my local Generac "technician" want ~$250 to come out and do 5-10 minutes worth of work (to reprogram and raise the output slightly), I decided it's easier and less costly (and probably more reliable) to simply install a buck/boost transformer on the generator's output, right up next to the transfer switch. A 1.5 kVa, 240x12v transformer (wired for "boost") will have more than enough capacity, and will raise the ~238/119 volt generator output to 250/125v. Wiring will be simple, since there's already OL protection at the Genset and in the panel. Just need to re-route the Genset output into the transformer (mounted right next to panel), then output of trans back into the xfer-switch breaker.

This will keep my radio gear happy when on the generator.

The other option would have been to "buck" the incoming utility voltage down to ~238-240v, but that would've required a larger transformer (3-5 kVa, for the 200 amp incoming service), with a lot more [big] wiring and extra [bigger] circuit breakers (or a fused disconnect)... which further increases costs.

Found a brand new buck/boost transformer on eBay for a very reasonable price... it's ordered and shipped. Hoping to have it all installed and wired by next week.

Thanks again for the couple of responses.

All the best!
~Al in West Texas
Birken Vogt
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That seems like a lot of work just to keep a dealer out of it, who might be your friend if something else goes wrong.
murphy
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Does Texas have its own grid that is not connected to the rest of the country?

The standard voltage on the grid in PA is 240/120 volts.
Chris
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I really think that you're thinking too much into this...

A buck/boost transformer doesn't (in my opinion) have a place in a residential application, especially when you can tune the voltage on the generator with a simple service call.

When we talked last I explained that because these units have a stepper motor that adjusts engine speed based on load to keep them at 3600 RPM, there is a chance that the voltage will spike a bit as large loads are removed and the stepper recovers. Amplifying that with a transformer just doesn't seem like a great idea.

I think I suggested a double conversion UPS attached to the radio gear which would convert any incoming voltage to a stable output regardless of the generator being on or the utility.
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Birken Vogt
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Another thought I had, was, how are you going to buck/boost a 3 wire circuit with a transformer?

You would need 2 x 120V transformers, or one with center tap and multi taps on both ends.

Or else you are going to have one leg that is 120 volts and one leg that is 130 volts with a single autotransformer.
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