Category Archives: Inverters
Some things to think about when buying a UPS system
Below are some general questions when buying a UPS system:
Off-line
An off-line unit would be the most basic UPS system as the load is supplied by raw mains until such times that the voltage or frequency would go outside the preset tolerance levels at which time the system would support the load via its battery. These units are primarily used for PC’s or servers but should not be used in an area were the local power supply is particularly unstable.
True online double conversion
True online double conversion UPS systems, due to the continual AC to DC followed by DC to AC conversion, provide a consistent quality of power. As the UPS output is independent of the mains input no matter what disturbances or fluctuations there may be on the mains supply there will always be a clean controlled output. This type of system is suitable for all applications were a high availability of supply is required.
Redundancy
Redundant systems are utilized in order to provide added resilience to further reduce the risk of a power failure. Multiple UPS systems are connected together sharing the load, this enables essential maintenance and repairs to be carried out on any of the connected modules without having to transfer the load to mains supply.
Scalability
Scalability is for instances when it is estimated that the load may increase in the future so the UPS system should be scaled up to match the demand. It is also used where the budget for the UPS requires that a smaller system can be purchased at the outset to suit the current load with additional modules
Communications
UPS systems have various options for communications such as volt free contacts for connection to the buildings BMS to network connectability enabling SNMP. It is best to decide on communication options from the outset so that the necessary cabling etc can be installed.
Contact Us
If you need any more information, or if we can help you in any way, then please contact us by sending us an email on sales@microsystemservices.com
Inverter-Battery buying tips and calculations
You must be having a hard time and may be even trying to get an inverter. But must be confused which inverter and battery to choose. Some may have bought them already but presently may not be sufficient to provide electric backup. So, I suggest you do some homework before buying or upgrading the inverter/battery.
Thumb rule is that you select inverter based on the power required and battery based on the backup time required.
Selecting Inverter:
Inverter rating (VA) must be greater than the total power required by the devices to be operated via inverter. So, first of all sum up the powers of all those devices. I have listed the power consumption value for some equipments below.
| Appliances | Power (Watts) |
| Laptop Computer / Digital Camera | 35-45 |
| 100W Light / 12″ Fan / 19″ Color TV | 100 |
| Computer / Printer / Fax | 300 |
After getting total powers in watt, you need to convert that to corresponding VA value; to compare with the inverter rating. conversion from watt to VA can be done using the equation below.
Power in VA = power in watt / power factor
power factor = 0.8
| Example: There is a 1 computer, 1 TV and 4 CFL lamps (5 watt each) then total power = 300+100+4×5 = 420 Watts. In VA that corresponds to 525 VA. So we need an inverter with rating greater than 525 VA . |
Selecting Battery:
For the battery selection the equation below summarizes all the points.
Battery Voltage x Battery AH rating = Required VA x Backup Time
Battery AH rating = Ampere-Hour rating of the battery
Backup Time in hours
We already have the Required VA as calulated from the total power required. Now we have to figure out ourselves the backup time required and decide to use 12 V or 24 V battery. Or we may combine batteries in series to sum up the voltage and get higher voltage.
After then we can calculate the AH rating and get a battery near that rating.
| Example: As for the previous case, Required VA = 525VA. If we require it for backup time of 6 hrs with 12V battery then battery AH rating = 525×6/12 = 262.5 AH. But if we use 24V battery then battery AH rating = 525×6/24 = 131.25 AH |
Also see:
How to a high efficiency UPS can save you more than 3 lakhs per year
Protect your equipments from high voltage fluctuations- video presentation
