It might be the Chinglish translation:
1 KVA is indeed 1000 W resistive. 0.6 pf is IMPOSSIBLE to apply to the input unless it's misinterpreted as 60% efficient. You would get the same result. A 0.6 pf is "60% efficient".
So I think things got lost in the translation.
So what does that mean? Probably that it can supply the Watts continuously, but can briefly say start a motor. In-rush has to be covered with the VA rating.
The power rating of the UPS
UPS have both maximum Watt ratings and maximum VA ratings. Neither the Watt nor the VA rating of a UPS may be exceeded. It is a de-facto standard in the industry that the Watt rating is approximately 60% of the VA rating for small UPS systems, this being the typical power factor of common personal computer loads. In some cases, UPS manufacturers only publish the VA rating of the UPS. For small UPS designed for computer loads, which have only a VA rating, it is appropriate to assume that the Watt rating of the UPS is 60% of the published VA rating. For larger UPS systems, it is becoming common to focus on the Watt rating of the UPS, and to have equal Watt and VA ratings for the UPS, because the Watt and VA ratings of the typical loads are equal.
Hi
These are the specifications of UPS system being used:
DC input 12V
AC output 220V, 50Hz
10A/20A charging current
Power factor 0.6
Power 1 kVA
Modified sine wave
The battery being used is 12V, 175Ah.
Q1:
If I go with mathematical calculation then I would say that the UPS could only supply 600W because power factor=real power/apparent power. I am still confused. Why does the UPS system have such a low power factor for itself? I had that it's a load which dictates power factor and not the supply (which in our case is UPS system). Even generators tend to have unity power factor.
Note to self: The inverter used in the UPS system could only produce 600W.
Please help me with the queries. Thank you.
Regards
PG
MrAl said:The 'output' is rated at 1kVA, and that alone tells you what you can connect to the output . That means you can connect a load that draws current times volts out equal to 1000 VA. If the output was 100vac for example then the max load current would be 10 amps, regardless of whether or not the load was reactive or purely resistive or a combination of the two. So for this inverter you could connect a 220v heater that dissipates 1000 watts if it is purely resistive.
In principle, this should be true 1000 W = 1000 VA, but it's not. With UPS specs, Watts seem to mean continuous and VA seems to mean surge.
Watts seems to always be less than VA. I invite you to disprove my theory.
MrAL said:I cant argue that they all do this, but what you are suggesting is that they use Watts to show the continuous rating and VA to show the peak rating. If they do that then they dont know how to rate an inverter properly. We could look for more inverters and see what gives here.
Totally agree 100%. What it probably does is allow the consumer to guess correctly most of the time.
The literature research done by me an PG in this thread supports the VA and Watts specifications. As I said earlier. Xantrax is manufacturer I would trust. They show Watts and Watts surge which is more like Watts and VA surge. Probably turned to Watts to be consumer friendly. I'd like to contact Xantrax.
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