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UPS Backup Time Calculator-Definition, Usage and Performance
The UPS allows the safe way for computers and connected equipment to shut down in an orderly manner. It depends on the size and design of the UPS to determine how long that power supply will be. There are generally four types of UPS; it is explained below:
How to calculate your UPS Back-up Time?
How do you use the UPS backup time calculator properly?
The Volt-Ampere(VA) rating of an inverter is the apparent power it can supply to power the appliances at any given point of time. It is calculated by summing the individual power ratings of all the appliances one wishes to run on inverter power. The sum obtained is then divided by the power factor because 100% efficiency is not attainable, and 15–20% efficiency is lost as heat. Generally, the power factor is between?0.7 to 0.8.
For example, suppose one wish to run the following appliances on inverter power:-
3 ceiling fans = 75W x 3 = 225W
1 Refrigerator = 175W
4 Fluorescent Tubes = 50W x 4 =200W
Total power consumption = 225W + 175W + 200W = 600W
Now, 600W is the power rating of all the appliances one would want to run on inverter power. Dividing 600 by power factor, i.e. 0.8 would yield the VA rating one should purchase an inverter with, i.e. 600 / 0.8 = 750 VA.
Therefore, for the above-stated energy requirement, a 900 VA inverter would be an appropriate choice.
What is the performance of the USP backup time calculator?
Here is a quick guide on calculating the inverter and battery backup time.
There are different capacities of inverters like 200VA, 250VA, 350VA, 400VA, 450VA, 500VA, 625VA, 1200VA, etc. The Load of the inverter should be chosen based on how many watts of appliances you power at a time.
How to convert from VA to Watts?
Volts x Ampere = VA (Volt Ampere)
Volts x Ampere x Power Factor = kW (Watts)
Power Factor = 0.8 (which is the max. power factor of the home standard)
If you want to run 200W of appliances then,
200 / 0.8 = 250VA
So, it would be best if you preferred the inverter of 250VA or more. 300VA inverter will be the best choice.
Similarly, the battery is an integral part of the inverter. The performance of the inverter depends on the connected battery and vice-versa.
The battery backup time in hours can be calculated using the following formula:
Backup Time = Battery AH x 12V x N x Efficiency of Battery / Load in Watts
Battery AH = Ampere Hour Capacity of Battery
N = Number of 12 V Batteries needed
The efficiency of battery = Generally, it is 0.8, which is the max. the power factor of home standard
Note: The inverter capacity is not used in backup time calculation.
Suppose I have a 60A battery. My Load is 150W. I have a single 12V battery. Generally, in-home standard, only a single 12V battery is used.
Backup Time = ( 60 x 12 x 1 x 0.8 / 150 ) hours
= 3.84 hours
Hence, an ups system serves multiple purposes:
- Protect against power interruptions
- Provide adequate power during short-term interruptions and “ride-through” time to convert to backup supply
- Refine the quality of the power as it reaches your building, office and equipment
Include a backup source for long-term outages, such as generators