UPSUninterruptible Power Supply

By Linda Kurniawati

OTP ELECTRICAL TOTAL EP INDONESIE

(Batch 3)2014

What the UPS is

An Uninterruptible Power Supply (UPS) is a device that has

an alternate source of energy that can provide electrical

power when the primary power source is temporarily

disabled.

What the Function for

To give several time for the genset for working properly.

To protect eqiuipments and systems of the electrical

failure.

To ensure there is continious power supply of electrical

power even the primary source is no longer present.

Types of Load

Critical Load

Essensial Load

Non Essensial Load

Critical Load

The load needs continuously electrical power as long as the production

process is running and a while after operation stops.

If the power no longer to supply, it could made mistake of operation,

injuries, accident, data loss, the production process stops and it can

endanger for human life.

For example : the process of instrumentation, computer,

telecommunication, monitoring system, fire system and etc.

Essensial Load

The load also needs continuously electrical power as long as the

production process is running and a while after operation stops.

If the power no longer to supply, it could give impact and influence the

quality and quantity of the product.

For example : Motor pumping unit, compressor, etc.

Non Essensial Load

The load doesn’t require continuously power supply.

If the power no longer to supply, it doesn’t directly influence the

production process. The present of loads just to satisfy the determine

standart of product.

For example : Lighting system, utility system, etc.

Types of UPS

Rotary UPS

A less common type of UPS which uses alternator to create the

electrical output.

Static UPS

A static device made of solid-state for producing electrical power

(no rotating devices are equipped).

Rotary UPS

Static UPS

•Converts AC supply to DC supply.

Rectifier/Charger

• Stores electrical energy.

Battery

•Convets DC supply to AC supply.

Inverter

•An automatic switch that can only be actived depanding on the condition of the UPS.

Static Switch

Main Components of Static UPS

Main Components

Diagram of Static UPS

Rectifier/Charger

Bridge Rectifier Circuit (single-phase)

Battery

Lead-Acid Battery

Sponge lead as negative electrode

Lead dioxide as positive electrode

Sulfuric acid solution as the electrolyte

Battery

Nickel-Cadmium Battery (mostly used)

Cadmium hydroxide as negative electrode

Nickel hydroxide as positive electrode

Potassium hydroxide solution as the electrolyte

Inverter

Inverter Circuit (single-phase)

Static Switch

Diagram of Static UPS

Normal Operation

Failure of the Main AC Supply

Standby Power Supply on Line

Bypass or Maintenance Mode

Operation of Static UPS

Normal Operation

The load is supplied by the charger (rectifier), the inverter and the

static switch, and S1 is closed.

Failure of the Main AC Supply

The charger stops and the battery powers the inverter and thus the

load. The operating time depands on the capacity of batteries.

Standby Power Supply on Line

S1 and S2 are closed. The switching occurs outomatically.

Bypass or Maintenance Mode

The load is supplied by the standby power supply directly through

S3.

Conclusion

UPS is used to give back up power supply to load which needs the existence of electrical power in under

normal and also emergency condition.

Three types of load : Critical Load, Essential Load and Non Essential Load.

The main components of the Static UPS: Rectifier/Charger, Battery, Inverter and Static Switch.

Four modes of configuration of Static UPS : Normal Operation, Failure of the Main AC Supply, Standby Power

Supply on Line, and Bypass or Maintenance Mode.