Frequently Asked Questions About UPS

What is UPS?

An Uninterruptible Power Supply is a device connected between the power source and a load (computer, fan, TV, etc.) to ensure that electrical flow is not interrupted. It is also called uninterruptible power source, UPS or battery/flywheel backup. UPS systems devices Use batteries to keep the load running for a period of time after a power failure. UPS systems cannot be confused with standby generators which do not provide protection from a momentary power interruption, or which may result in a Momentary power interruption when it is switched into service, whether manually or automatically. UPS systems usually provide protection against power surges, brownouts and line noise as well.

What’s the usage of UPS?

Every UPS will supply power to load (such as a computer, fan, TV, lights or medical equipment) when mains power fails. It may also regulate the power and prevent the spikes, brownouts, interference and other unwanted problems from damaging the supported equipment.

How long can the UPS support for my equipment running?

As long as you want, providing you buy enough batteries and the charging system is up to it. After about eight hours it`s usually more cost-effective to buy a generator, with a short runtime UPS to bridge the generator start-up gap.

What`s lifetime of a UPS? 

Most plug-in UPS are good for at least ten years. We`d advise you to change the batteries every twelve months to eighteen months.

What is called "Online UPS"?

CHADI online UPS as the batteries are always connected to the inverter, so that no power transfer switches are necessary. When power loss occurs, the rectifier simply drops out of the circuit and the batteries keep the power steady and unchanged. When power is restored, the rectifier resumes carrying most of the load and begins charging the batteries.

What's the difference between Low Frequency and High Frequency UPS?

Low frequency UPS is double-conversion UPS which provides a layer of insulation from power quality problems. It allows control of output voltage and frequency regardless of input voltage and frequency.Physically the double-conversion UPS are equipped with mass transformers for both input and output. 

The HF UPS converts the battery DC to a high voltage CD, using a high frequency switch-mode converter. The HVDC goes through an array of FET transistors, which are driven to generate an approximation of AC mains. Cheaper ones make a stepped square wave, better ones a near sine wave.That HV converter is relatively lightweight. Most of the mass of such an inverter is the battery.

For the low frequency type, the DC goes into an iron power transformer (which is usually dual function as the battery charger transformer), and driven on the low voltage side to simulate AC, which directly comes out the 220V (or 120V) side of the transformer. The Iron transformer is usually pretty large, and a good part of the mass of the inverter, along with the battery.

What is called "Off-line UPS"?

In this type of UPS, the primary power source is line power from the main utility, and the secondary power source is the battery. The battery charger is using line power to charge the battery, and the battery and inverter are waiting "on standby" until they are needed. When the line power fails, the transfer switch changes to the secondary power source. When line power is restored, the UPS switches back. 

What is called "Line Interactive UPS"?

Line Interactive UPS under normal condition smooth’s and to some degree regulates the input AC voltage by a filter and a tap-changing transformer. The bi-directional inverter/charger is always connected to the output of the UPS and uses a portion of AC power to keep the battery charged. When the input power fails, the transfer switch disconnects AC input and the battery/inverter provides output power. Its typical efficiency is 90-96%. This type is currently the most common design in 500 VA - 2000 VA power range.

What is called "Inverter"?

The main power AC is supplied to the inverter, and it is transformed into DC simultaneously, which keeps charging the battery continuously. Inverter’s output voltage is always dependent upon input voltage. There is a sensor and relay structure that always monitors the ON or OFF status of the main. Then it changes the DC power from the battery to AC current, and that flows to the electronic equipment. However, SIMTEK pure sine wave inverters available today that make the use of UPS redundant as they can supply uninterrupted power supply in the case of a power failure.

What is difference between “UPS & Inverter"?

While both devices provide backup power during mains outage, the only difference is the time lag. While a UPS instantly starts supply, with an inverter there is a lag of around half a second which is unacceptable if the device is a computer that you are working upon. For the rest of the appliances, however, this time lag is acceptable and this is the reason UPS is used only for computers whereas inverters are used for all other household and office appliances.