itilldo
Charter Member
Buying a generator 101:
Generators are like a stereo. Ratings on them are always listed as maximum (peak) output, not continuous (RMS) duty. All generators are subject to a performance factor (PF) rating. Most use a .80 factor, i.e. a 10KW is 8 continuous, 10 peak. Some of the higher quality one's (Yamaha for one) use a .90 PF.
What does this mean to the consumer?? Your genset will produce its maximum rating (10kw) for a short period of time to handle surges and overloads. It will produce the rated output (8kw) on a “continuous” basis. Your generator may also have a “surge” rating. AFAIK, this rating has no standards, but instead seems to be how much of a load the genny will handle for a brief period without the voltage dropping below an undetermined level. As an example, there is a site that lists the Yamaha YG6600DE as having a surge capacity of 18,000 watts. This genset is rated @ 6600 peak, 6000 continuous. On a load bank it will hold a 6KW load @ 123 volts, 60 – 61 HZ all day long. Bump it to 7KW and after a few moments it begins to lose voltage, dropping to approx 110 volts. Bump it to 8KW, and the voltage is below 100 volts, and the engine is at the point of stalling. Whatever load you have on it, let’s say a fridge, is at risk of burning out it’s compressor / fan motors due to low voltage, and if the genny stalls, the risk is compounded.
Then, we get into the next bugaboo: Duty cycles. Not all generators / engines are manufactured to perform at rated output full-time. A duty cycle is how many minutes out of the hour it can do this.. Bummer is most generator manufacturers hide this information. So, your 8KW genset may actually be capable of producing that power for 6 minutes out of every ten without damaging it, or a 60% duty cycle.. Last but not least, a lot of the cheaper genset's use a smaller engine. It is always running at or exceeding its maximum capacity, shortening its life.. There is no replacement for displacement
To connect to the house: Get a transfer switch. If you’re needing to connect now, first of all yank the meter.. Not only does this prevent feedback from your genny to the lines, it prevents feedback from the lines to your genny.. It also gives the linemen a visual indicator that you have isolated your house from them, and they are not going to die working on your lines.. (FWIW, I have a 400-amp transfer switch on my house, and I still yank the meter when a genny is in use. Not necessary, but again, it's that visual thing..) Next, you need to inspect all the wiring for damage from flying debris. Outside outlets are a prime suspect. Check inside the panels and visually check your walls for water intrusion.. Then, you can wire the genny into the main panel. You want to connect to the 240 side of the genny and let the panel split the voltage. Your genset has two sets of windings, both make 120. If you pull off the one winding all the time, you will burn it up. If you pull evenly across both windings, it will last much longer.. Most of the gensets today have a four-prong connector, separating the neutral from the ground... Your electrician can help you connect it, but make sure you use all four connections if provided.. The generator should be grounded also; I go to the ground rod for my main panel.
Diesel vs Propane: On the average, a 20KW propane burns about 4 GPH. My 30KW diesel burns 17 gallons a day running 24/7. A lot of my customers buy the diesel units so they can switch it to 3 phase during the day for the office/shop, single phase at night for the house. Another drawback to the propane units is the fact that the regulators in them tend to go bad and come out adjustment. Diaphragms dry rot, fuel doesn’t flow, or even worse, leaks.
So, where are we now? Budget for the most generator you can afford.. Then BUY the next size up... FWIW, I sell more gensets the second week after a storm than the first. The people buying them are on their second generator of the event, the first one is toast…
is there info you have for a manual switch gear
