What is UPS? How does it work?
In this article on UPS you are going to see, what is UPS? How does it work? Uninterrupted Power Supply – Types of UPS, on-line UPS, off-line UPS, UPS checklist, and maintenance are explained in detail. Hope this will be helpful for you.
What is UPS?
Uninterrupted Power Supply (UPS) – A static device made up of electrical and electronic components. When the power supply fails or the voltage is abnormal, then supplies power from the battery back up without interruption. It is called UPS.
There is a connection of electrical power in any organization, organization, or house. When this electrical power fails, all electrically powered devices are switched off. Some devices in this suddenly get tied up and cause damage to us.
In industrial units, in hospitals, cinema halls, generators are used as standby power. But there is a difference between standby power and UPS power.
Standby power: After the main power supply fails, the generator is switched on and the supply is taken in the line. Here there is such a time in the middle of the power that there is no electricity there. which is called blackout.
Full-Form Of UPS -: UNINTERRUPTED POWER SUPPLY
The UPS does not allow the power supply to break. Even our office has a UPS supply, and if there is a power failure, we will not even know. That is why it is called an Uninterrupted power supply.
Like we have a computer but UPS is not installed in it. When we work in it, if there is a power failure at the same time, then its data can be lost. If the PC gets stuck even in power fluctuations, it can cause damage.
UPS (Uninterrupted Power Supply) is used more in the factory. If the plant has systems like DCS and PLC then UPS supply is necessary here. Because the entire plant is controlled from here. If the power supply of the plant fails, it is controlled by DCS Scada itself.
It is very important to have the power of ups in the hospital. If a patient's operation is going on in the operation theater and if the power fails at such time, then there is a problem. That's why the UPS power is always there in the hospital.
Plant lighting is very important. We all understand the importance of light in the night time. There are different operations in different processes in the plant. In this case, an emergency light is installed. Which is connected to Uninterrupted Power Supply.
Apart from this, there is such equipment in the plant which should not be affected by power failure. UPS (Uninterrupted Power Supply) is also used in such a place.
How to do UPS Selection?
1 How much time backup power do we need on UPS?
2 How much load current is going to be by UPS?
3 Where will be the location of UPS?
4 Which device we have to give backup power. The criticality of the equipment?
5 How much is our budget?
UPS is rated in VA and KVA. Because the power factor of the load is not fixed.
VA stands for Volt*Ampere.
KVA This is the big unit of VA. kilo volt-ampere.
The inverter which is used for our home is usually 800VA to 1000VA in capacity. With this, we can run four fans and four 10W lights for 8 to 10 hours.
Power failure in the electrical system can be due to any number of reasons. Which causes a voltage spike. Effect of the surge in voltage. voltage deep. and having a harmonic effect. All these factors can damage electrical equipment.
Which has a direct effect on production. UPS (Uninterrupted Power Supply) is used for the constant power supply of critical equipment running on electrical power.
Most of it is needed to continue the process in industrial units. Happens in medical service. Happens in telecommunication. It is used to maintain the data system of computers. And it happens to keep the network live.
The UPS system ensures continuous correct power. That is why it is used for emergency power.
Types Of UPS
There are three main types of UPS.
- Standby UPS (Off-Line UPS)
- Line Interactive UPS
- Online UPS – Online UPS
There are two types of UPS based on phase.
- Single Phase UPS
- Three Phase UPS
Standby UPS (Off-Line UPS)
Standby UPS (Uninterrupted Power Supply) is also called off-line UPS. This type of UPS is mostly used for PC. This is a basic UPS. In which there is surge protection and battery backup. We can see this in the diagram of UPS given below.
Off-line UPS
In which the incoming power is 230 volts, or it is a single-phase UPS. Two lines come out of the output of the main switch. A line connects directly to the load through the "NC" contact of the static switch.
That is, in the normal condition of off-line UPS, there is no converter, battery, charger, inverter in some line. Supply goes directly to the equipment.
The second line coming out of the main switch goes to the converter. where is the rectifier unit. There the AC supply is converted to DC. The DC supply from the rectifier is supplied to the battery charger. Where the battery is charged.
The output of the battery is the DC supply. The supply we use in the equipment is AC, that's why matching with the battery. The DC has to be converted into AC. An inverter is installed to convert the DC supply to AC.
The AC supply from the output of the inverter goes to the 'NO' contact of the static switch. When the main power failure occurs, the contact of the static switch is changed.
The 'NO' contact becomes 'NC' where the battery is backed up. This battery backup is converted into AC from the inverter and we get it in the device.
Off-line, UPS has surge protection which protects at the time of the surge.
Advantage Of OFF-LINE mode UPS
- Offline UPS is cheaper in price.
- In this, the charger of the battery does not work continuously, therefore, its working capacity is good.
- The circuit of OFF-LINE UPS is very simple. which can be easily understood.
Disadvantage Off-Line mode UPS
- The equipment is directly connected to the main power line, hence, protection against voltage variation spike, the surge is not available.
- When there is a power failure, it takes time for the battery to be transferred to the backup inverter.
- We cannot call Off-line UPS as Perfect Uninterrupted Power Supply.
OFF-LINE UPS USES
- Off-line UPS supply is used in computer, printer scanner.
- Used in emergency power lighting.
What is online UPS?
We can call this UPS a Perfect Uninterrupted Power Supply. After connecting with this type of UPS load, we can rest assured. Whether there is a power supply failure, voltage fluctuation, surge, or spike, it does not affect. This up gives us continuous and accurate output without any kind of interruption.
In this type of UPS, the battery is always in line. It does not require contact with the static switch at the time of change over. The battery charger also remains in line. AC to DC converter, battery, inverter after the load is connected.
Due to this being in the entire circuit line, the temperature of the ups thus increases. That is why it is mostly kept in the air conditioner room.
Online UPS also has a bypass switch. If there is an internal fault in the UPS, then in such a situation the load will go to the bypass switch. But there will be no breakdown.
Advantages of Online UPS
- In this type of ups, there is an isolation switch between the main supply and the load. If needed, you can work in a bind.
- The load is continuously received from the inverter, so the voltage does not change in any way.
- It takes practically zero time to transfer the load at the time of power failure. That is, the load is transferred without any kind of interruption.
- In this type of UPS, the output constant is also available due to any kind of spike, surge, blackout or burn.
- If there is a fault in the UPS, then it gets activated by bypass.
- Voltage regulation is very good. There is no effect of any kind of fluxation.
The disadvantage of Online UPS
- Online UPS It is costlier than off-line UPS.
- The efficiency of the inverter circuit is reduced due to the continuous load being in the line.
- Rectifier, Inverter, Battery, and Charger This entire circuit being live increases its power consumption.
- The circuit of online UPS is a bit complicated, so it takes time to find the problem.
- The temperature of the room has to be maintained.
Application of Online UPS
- Used in the ICU (Intensive Care Unit) of the hospital.
- Used in the operation theater of the hospital.
- For running equipment like motor and VFD in the continuous process plant.
- Used in 4-DCS (Digital Control System) and PLC (Programmable Logic Control).
Line Interactive UPS
Line interactive UPS, This is a type of off-line UPS only. In this type of UPS, the AVR card is installed after the main power supply. This card regulates the voltage
If there is fluxation, under or over voltage in the incoming voltage, then in such a situation it regulates the AVR voltage. And according to the setting that we have made, we get the voltage at the output.
Preventive Maintenance for UPS
Daily check-up
Industries have large capacity UPS whose parameter readings are checked every day. If any abnormality is found then action is taken.
Quarterly
Visual Inspection is done. In which any burning smell, connection tightness, insulation, and cable overheat are checked.
semi-annually
- is visually checked.
- A leakage check of the battery and capacitor is done.
- The entire ups are vacuumed and cleaned with cotton waste.
- The air conditioner maintaining the room temperature is checked.
Annually
- Thermal scanning of UPS is done. All electrical connections and control cards are temperature checked. If there is a problem it is fixed.
- The complete operation of the uninterrupted power supply is tested. Battery backup is checked by isolating the main power. Each cell is checked with a load tester.
- Protection of ups transfer switch, maintenance bypass switch, and the circuit breaker is checked.
- The connection tightness of the battery terminal link and the control connection tightness is checked.
How to find UPS backup calculation?
Formula to calculate UPS battery backup : C=(P *B)/(V *E *D)
C =Battery Capacity, Unit Ampere* Hour (AH)
P = load power, unit vote (W )
B = Battery backup time, unit hour (H)
V = battery voltage, unit volt (V)
E = inverter efficiency
D = battery discharge ratio
The longer the battery backup time, the better the efficiency.
Names of UPS making company- Emerson, luminous, APC, etc.
Names of battery making Company- Luminous, amaron, Exide, etc.
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