Generator stability questions
lazza
Solar Expert Posts: 336 ✭✭✭
HI Forum
We've recencently been working with an "all-in-one" inverter-charger system that uses grid or generator current to charge the batteries as well as charging via solar.
When the voltage and frequency of the input from the generator/grid is stable, it works brilliantly. However, clients often have small Honda-type cheap generators that give varying voltage and what seems worse, unstable frequencies. With this instability the inverter´s charger system struggles to give the normal current that it's supposed to to the batteries.
My questions are:
- is it normal for these small generators to be so unstable-? If so, their compatibility with inverter/chargers is dubious.
- could it be that they need their AVR replacing?
- what causes the frequency variations and will replacing the AVR deal with that too??
We've recencently been working with an "all-in-one" inverter-charger system that uses grid or generator current to charge the batteries as well as charging via solar.
When the voltage and frequency of the input from the generator/grid is stable, it works brilliantly. However, clients often have small Honda-type cheap generators that give varying voltage and what seems worse, unstable frequencies. With this instability the inverter´s charger system struggles to give the normal current that it's supposed to to the batteries.
My questions are:
- is it normal for these small generators to be so unstable-? If so, their compatibility with inverter/chargers is dubious.
- could it be that they need their AVR replacing?
- what causes the frequency variations and will replacing the AVR deal with that too??
Comments
-
Re: Generator stability questions
It is normal for standard fixed RPM generators to be unstable in Voltage and frequency. The greater the load change in relation to the generator's capacity the more unstable it becomes.
Most of the small Hondas (at least what we get around here) are inverter-generators which are extremely stable for both Voltage and frequency.
It is also normal for any system expecting generator power input to recognize a wider range of V & f in order to function properly.
So whether or not the generator(s) in question works properly depends on exactly which gen it is. The output can be tested to see if it meets manufacturer's specifications. If it does, there's nothing wrong with it; the application is unsuited. -
Re: Generator stability questions
Lazza, I use a P3 Kill a Watt meter on my stuff to check out the Frequency, PF and Voltage. Have found the 1000w Honda Inverter gens I have to be ~ 123 V and dead steady loads (light) or not. The non inverter gen is set at about 125V so that when a ~ 10 amp load is applied it comes down to 60 Hz, but it too is quite stable under load, Jap Mitsubishi motor on it. The 3000w Honda hardly blips when applying same 10A load (Sliding miter saw)
KID #51B 4s 140W to 24V 900Ah C&D AGM
CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM
Cotek ST1500W 24V Inverter,OmniCharge 3024,
2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
West Chilcotin, BC, Canada -
Re: Generator stability questions
What sort of "load" does your "all-in-one" inverter-charger system present to the generator? Is it a good power factor ? If a generator is not matched to the load, then poor results can be expectedPowerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister , -
Re: Generator stability questions
It takes two, both the generator and the Inverter to be able to work together. The Inverters charging control has to Ramp up the amperage to the Charger set limit, it cannot over shoot or go wide open and then cut it's self back. It has to be able to be set in small increments of no more that 1-2 amps. The ACin limits have to able to be set in 1 amp increments.
Inverter generators take care of themselves unless you overload them. A small non inverter Generator's RPM usually correlates the voltage and hertz of the output. Example : 125 V is 62-63 HZ. Most inverters will not accept HZ this high, 120V is 60hz. Sometimes putting a dummy load on them will get them to qualify, then you can start to load them a little at a time and remove the dummy load. The Governor has to be responsive enough to keep the RPM steady.
Over all the best Inverter / Charger is the Outbacks, they have a lot of flexibility built in the firmware. Brand X is 5,10,15,20,25,30 a small generator cannot adjust to those limits that fast. -
Re: Generator stability questions
THanks for the replies.
All I know is that the frequency varies between 42Hz and 48Hz (50Hz system).. the frequency doesnt stay around any fixed point.. which to me harks of a problem with the generator.. but i could be wrong?? -
Re: Generator stability questionsTHanks for the replies.
All I know is that the frequency varies between 42Hz and 48Hz (50Hz system).. the frequency doesnt stay around any fixed point.. which to me harks of a problem with the generator.. but i could be wrong?? -
Re: Generator stability questions
If the gen's frequency is only hitting a high of 48 then it is running too slow. Usually they want the gen loaded 25%-50% of capacity for speed/frequency/Voltage adjustment. The gen's specs should tell you what range it is meant to operate in. As I said before it depends on which generator. If its specs are too loose to be any good, you can't use it. If it does not operate within spec it's defective. You have to remove the variables to find the problem. -
Re: Generator stability questionsCariboocoot wrote: »If the gen's frequency is only hitting a high of 48 then it is running too slow. Usually they want the gen loaded 25%-50% of capacity for speed/frequency/Voltage adjustment. The gen's specs should tell you what range it is meant to operate in. As I said before it depends on which generator. If its specs are too loose to be any good, you can't use it. If it does not operate within spec it's defective. You have to remove the variables to find the problem.
If your going to try a dummy load it needs to be variable. I have a old hot plate that I have used that has a variable rheostat on it, marked so you can repeat the loading. You have to set the governed speed and also the sensitivity. My best guess your not going to be successful. It's really hard to get the inverter to do pass through and charge at the same time with a small non inverter generator, but you might to get it to charge. Allowing multiple transfers on the Relays is not a good thing to do, as they wear out fast and fail.
Categories
- All Categories
- 222 Forum & Website
- 130 Solar Forum News and Announcements
- 1.3K Solar News, Reviews, & Product Announcements
- 192 Solar Information links & sources, event announcements
- 888 Solar Product Reviews & Opinions
- 254 Solar Skeptics, Hype, & Scams Corner
- 22.4K Solar Electric Power, Wind Power & Balance of System
- 3.5K General Solar Power Topics
- 6.7K Solar Beginners Corner
- 1K PV Installers Forum - NEC, Wiring, Installation
- 2K Advanced Solar Electric Technical Forum
- 5.5K Off Grid Solar & Battery Systems
- 426 Caravan, Recreational Vehicle, and Marine Power Systems
- 1.1K Grid Tie and Grid Interactive Systems
- 651 Solar Water Pumping
- 815 Wind Power Generation
- 624 Energy Use & Conservation
- 611 Discussion Forums/Café
- 304 In the Weeds--Member's Choice
- 75 Construction
- 124 New Battery Technologies
- 108 Old Battery Tech Discussions
- 3.8K Solar News - Automatic Feed
- 3.8K Solar Energy News RSS Feed