Harbor Freight Predator 3500
Any comments on the Predator 3500 invertor generator? They advertise this unit as being Super Quiet (58 dB). It normally sells for around $850. However, I have been getting email coupons lately for...
Forum Discussion
Some UPS units handle generators better than others.
Non inverter gens typically run a bit higher in output frequency (61HZ-62HZ) when unloaded, when loaded 50% will be spot on at 60Hz and when fully loaded will sag to 58Hz-59Hz..
Many UPS units are looking for 60Hz +(-).1-.2 Hz and anything outside of that the UPS will switch back and forth between gen and inverter..
UPS units monitor the frequency closely, they must be able to synchronize with the incoming 120V to provide seamless transfer between incoming line and the inverter. Without the synchronization the devices attached could be presented with voltage spikes or surges when switching.
What happens is the gens are set to run slightly faster unloaded and when loaded the engine RPM will sag a bit affecting the output frequency. This is done so the voltage will be a bit high unloaded and when loaded the voltage will not sag below acceptable levels.
I have had a variety of APC UPS units, some Tripplite UPS units also.. Most of the APC units are older units and seem to work well on gen, have one much newer APC that hates the gen when it is unloaded but works fine as long as there is a small load on the gen.. The Tripplites all seem to be happy and cope well with running on a gen loaded or unloaded..
Now as far as sinewave "quality" of a HF inverter gen goes, you make a fair point. May or may not be as "clean" as a Honda inverter gen, but keep in mind that pretty much all low cost UPS units are MSW and the cheapo low cost UPS units that claim PSW may not be really PSW but actually MSW.. So, if it works on a cheap UPS, it most likely will be perfectly fine running from a HF or other Chinese Import inverter gen.
Non inverter gens typically run a bit higher in output frequency (61HZ-62HZ) when unloaded, when loaded 50% will be spot on at 60Hz and when fully loaded will sag to 58Hz-59Hz..
Many UPS units are looking for 60Hz +(-).1-.2 Hz and anything outside of that the UPS will switch back and forth between gen and inverter..
UPS units monitor the frequency closely, they must be able to synchronize with the incoming 120V to provide seamless transfer between incoming line and the inverter. Without the synchronization the devices attached could be presented with voltage spikes or surges when switching.
What happens is the gens are set to run slightly faster unloaded and when loaded the engine RPM will sag a bit affecting the output frequency. This is done so the voltage will be a bit high unloaded and when loaded the voltage will not sag below acceptable levels.
I have had a variety of APC UPS units, some Tripplite UPS units also.. Most of the APC units are older units and seem to work well on gen, have one much newer APC that hates the gen when it is unloaded but works fine as long as there is a small load on the gen.. The Tripplites all seem to be happy and cope well with running on a gen loaded or unloaded..
Now as far as sinewave "quality" of a HF inverter gen goes, you make a fair point. May or may not be as "clean" as a Honda inverter gen, but keep in mind that pretty much all low cost UPS units are MSW and the cheapo low cost UPS units that claim PSW may not be really PSW but actually MSW.. So, if it works on a cheap UPS, it most likely will be perfectly fine running from a HF or other Chinese Import inverter gen.
