Power outage prevention device - What is the difference between an emergency generator and a UPS?

In the previous article, we learned about various power supply problems on the transmitting and receiving sides. In this article, we will learn about measures to protect electrical equipment from these power supply problems.

Power outage prevention equipment - What is the difference between an emergency generator and a UPS?

When you think of power outage countermeasures, what comes to mind is probably an emergency generator. Emergency generators installed in general companies and public facilities can generate power during a power outage and supply electricity to facilities for a long period of time. However, it takes about one minute for a generator to start generating electricity and send out electricity after a power outage. Also, unlike commercial power sources provided by power companies, not only the voltage but also the frequency can be unstable.
Emergency generators are suitable for dealing with long-term power outages, but they are not suitable for dealing with power supply problems such as momentary interruptions and drops and harmonics, which we learned about in the previous article.

Another type of power outage countermeasure is the UPS (Uninterruptible Power Supplies). This supplies clean electricity using an on-board storage device. Therefore, it is used as a countermeasure against power troubles such as voltage abnormalities and frequency abnormalities, including "momentary power outages and dips."

Power outage prevention equipment - What are the types of UPS power storage devices?

The source of electricity supplied by a UPS is a storage device such as a battery, and the characteristics of the UPS vary greatly depending on the type of device.
There are four common types of power storage devices: lead-acid batteries, nickel-metal hydride batteries, lithium-ion batteries, and electric double-layer capacitors. Lead-acid batteries and electric double-layer capacitors are the most commonly used in UPS.

1 Lead-acid battery

Because they are relatively inexpensive, they are the mainstream storage battery installed in UPS. They are advantageous when a relatively long backup time of 5 minutes or more is required, but their lifespan decreases with increasing number of charge/discharge cycles.

2 Nickel-metal hydride battery and lithium-ion battery

In terms of characteristics, they have better expected lifespan and storage capacity per volume than lead-acid batteries, and they are also highly durable when charged and discharged, but because they are expensive, they are rarely used in UPS.

3. Electric double layer capacitor (capacitor)

Electric double layer capacitors are also called capacitors. They are suitable for devices to deal with momentary drops and interruptions because they can instantly store and release large amounts of electricity. Also, unlike storage batteries, the charging and discharging mechanism is not a chemical reaction, so there is little deterioration due to charging and discharging, and they have a long life. However, they are not suitable for storing large amounts of power.

Maintenance costs also vary depending on the type of power storage device. If you want to keep maintenance costs down and even if the initial investment is a little higher, you may choose a power storage device with a long expected lifespan. By combining a power storage device and a power supply method, a UPS can deal with a variety of power supply problems. In the next article, let's learn about UPS power supply methods together.

Written by: Toshiyuki Nishizawa, Senior Sales Engineer, Sales Division, SANYO DENKI CO., LTD.

release date: 2016-12-01 00:00