The Secure Power knowledge base aims to give you the information you need to navigate the jargon and deliver straightforward advice around the terminology used within uninterruptible power systems.
Ampere is the base measurement of electrical current. Describing the electromagnetic force between two conductors, the measurement is commonly referred to as Amps, or simply “A”.
Amps are important to the input of a UPS and all other electrical equipment, they are used to correctly size the fuses and cables that will provide power to the devices.
When you choose a UPS, knowing the maximum Amperage it requires will allow you to check that the fuses and cables in front of the UPS are sized correctly. In the event, the UPS malfunctions or a cable shorted, the fusing or circuit breaker which is only sized to provide the expected amperage, will trip. This prevents further power from being provided and prevents the continuation of the issue and prevents damage to the equipment.
To calculate Amperage we can use Ohms Law. Three measurements are involved in this electrical law, from any two, the third can be calculated.
- AMPS = WATTS ÷ VOLTS
- VOLTS = WATTS ÷ AMPS
- WATTS = AMPS x VOLTS
In a typical example, you may need to know the Amperage a 3000W UPS. We already know the voltage will be 240V s ou calculation would be;
- 3000W ÷ 240V = 12.5A
From the above calculation, we would know that our device would require a 13A Fuse, should fuse rating be exceeded the fuse would melt stopping the current.
Utility power isn’t always what it should be, the input of the UPS is where it is measured.