UNINTERRUPTIBLE POWER SUPPLY

1. Power Fundamentals2. Power Problems. * Types of Power Problem. * Solutions/Protection.1. Types Of UPS systems.2. UPS tech. Specs Fundamentals. 1) Power Factor2) Crest Factor3) Voltage Regulation4) a) Line Interactive specs.

b) On Line specs.1. Battery.2. Power Drawn by Computer.3. Comparison Of Line Interactive & On-Line UPS systems.

INDEX:INDEX:• POWER FUNDAMENTALS• POWER PROBLEMS (a)

TYPES (b) PROTECTION

• UPS SYSTEMS• TYPES OF UPS• DIFFERENCE BETWEEN

LINE INTERACTIVE AND ON LINE UPS

• TECHNICAL TERMS ASSOCIATED WITH UPS

• BATTERIES

DATEX

POWER FUNDAMENTALS

• VOLTAGE• CURRENT• RESISTANCE• DC VOLTAGE • AC VOLTAGE• POWER• FREQUENCY• WAVEFORM• TRANSFORMER

Power FundamentalsPower Fundamentals• VoltageVoltage : is the source of power that makes

the current flow and helps the electrical appliances to perform their functions.

• Symbol: V Measured in: Volts. In our household we get : 220volts

V O L T A G E

V o l t a g e i s t h e e l e c t r i c a l f o r c e t h a t m o v e se l e c t r o n s t h r o u g h a c o n d u c t o r . V o l t a g e i se l e c t r i c a l p r e s s u r e a l s o k n o w n a s E M F ( E l e c t r oM o t i v e F o r c e ) t h a t p u s h e s e l e c t r o n s .T h e g r e a t e r t h e d i ff e r e n c e i n e l e c t r i c a l p o t e n t i a lp u s h ( d i ff e r e n c e b e t w e e n p o s i t i v e a n d n e g a t i v e ) ,t h e g r e a t e r t h e v o l t a g e f o r c e p o t e n t i a l .

MEASUREMENT

A VOLTMETER measures the voltagepotential across or parallel to the circuit.TheVoltmeter measures the amount of electricalpressure difference between two pointsbeing measured.Voltage can exist betweentwo points without electron flow.

CURRENT (AMPERES)

CURRENT is the quantity or flow rate of electrons moving past a point within one second. Current flow is also known as amperage, or amps for short. It is similar to flow of water in a pipe.

Higher voltage will produce higher current flow, and lower voltage will produce lower current flow. Just like higher pressure makes more water flow, and less pressure means less water flow.

MEASUREMENT Of Current

An AMMETERAMMETER measures the quantity of current flow.

Ammeters are placed in series (inline) to count the

electrons passing through it.

ExampleExample: A water meter counts the gallons of water

flowing through it.

Power FundamentalsPower Fundamentals

• CurrentCurrent : : It refers to flow of electric charge.Current has been the result of motion of electrons or ions under the influence of an e.m.f. or we can simply say it is a flow of electrically charged electrons.

• Symbol: I Measured in : Amperes (A).

Electrical Fundamentals

Units of measurement of Current

Current flow is measured in units called Amperes or AMPS.

Amperage measurements can use different value prefixes, such as micro-amp, milli-amp, and Amp.

AMPERAGE Symbol µAµA mA mA A A Pronounced Microamp milliamp Amp Multiplier 0.000001 0.001 1

RESISTANCE

Resistance is the force that reduces or stops the flow of electrons. It opposes voltage.

Higher resistance will decrease the flow of electrons and lower resistance will allow more electrons to flow.

Therefore a Load with less resistance will cause more current to flow through it. That is why a short circuit in an electrical line causes infinite amount of current to flow, as there is zero resistance.This causes heating

and eventually burning of the wire.

MEASUREMENTMEASUREMENT

An OHMMETER OHMMETER measures the resistance of an electrical circuit or component. No voltage can be applied while the

ohmmeter is connected, or damage to the meter will occur.

Example:Example: Water flows through a garden hose, and someone steps on the hose. The greater the pressure

placed on the hose, the greater the hose restriction and the less water flows.

RESISTANCE FACTORSRESISTANCE FACTORS

Various factors can affect the resistance. These include:

LENGTH of the conductor. The longer the conductor, the higher the resistance.

DIAMETER of the conductor. The narrower the conductor, the higher the resistance.

TEMPERATURE of the material. Depending on the material, most will increase resistance as

temperature increases.

PHYSICAL CONDITION (DAMAGE) to the material. Any damage will increase resistance.

TYPE of MATERIAL used. Various materials have a wide range of resistances.

DIRECT CURRENT (DC)DIRECT CURRENT (DC)

Electricity with electrons flowing in only one direction is called Direct Current or DC.

DC electrical systems are used in cars.

ALTERNATING CURRENT (AC)ALTERNATING CURRENT (AC)

Electricity with electrons flowing back and forth, negative - positive- negative, is called Alternating Current, or AC.

The electrical appliances in your home use AC power.

Power FundamentalsPower Fundamentals

• Power Power :It may be defined as the rate of energy transfer (or work done) by or to a system.In an electrical system power has been given by V I, where V is the potential difference across a conductor and I the current through it.

• Symbol : P Measured in : Watts(it is the energy transfer in joules per second).

Power ( P ) = Volts X Amp. ( VA)

Another unit for power is Watts.

What is the relation between VA and watts ?

There are two types of electrical loads

1. Purely resitive

2. Inductive or Capacitive collectively called reactive loads.

In purelyIn purely resistive loads resistive loads

VA = Watts or VA is same as watts.

Examples of purely resistive loads are

Electric Bulbs, heaters, toasters etc.

What it means is that the load is consuming and converting all electrical energy into

heat and/or light energy.

There are other types of loads which behave in a different manner, when a voltage is applied to them a current flows

through them but they do not consume all the current passing through. Examples of such loads are

Motors like in Fans, Air conditioners, transformers,elevators etc.

Some amount of current keeps flowing in the system without being consumed. In this case

Watts VAand VA > watts

The ratio of VA to Watts in such types of loads is called Power factorPower factor.

Ø = watts / VA

Sine Wave Form

One Cycle

T

Frequency (f ) = 1/ TPeak Voltage = 320 V

R.M.S. Voltage = 220 VAverage Voltage = 207 V

T = 20 msec, f = 1/20 m sec = 50 Hz

A.C. Voltage as it comes in our householdsA.C. Voltage as it comes in our households

The common voltage which comes in our households is known as Sine Wave.

As is clear from the diag. This voltage keeps alternating between positive and negative.

It starts from Zero, continuously increases to reach a peak of about 320 Volts, then starts decreasing to zero again and

continues the reducing trend to reach a negative peak of -320 V. It then again starts increasing to Zero Volts. This is one complete

cycle, which is then repeated again and again.

Time taken to complete one cycle is 20 milisecond.And it traverses 50 cycles in one second. This is known as

frequency.The peak AC voltage is 320 Volts , and RMS voltage is 220 Volts.

TransformerTransformer• A device which is used for changing the voltage of an

alternating supply. Transformers are not having moving parts and operate by the current in one coil, the Primary winding, electromagnetically inducing a current in another , the Secondary winding,which forms part of a separate electrical circuit.The ratio of the voltages in the primary and secondary circuits, V1/V2 has been approx. equal to the ratio of the number of turns in the primary and secondary coils .

• STEP UP transformers are used to increase voltage and reduce the current of the output from power stations so that losses in transmisssion lines are minimised.The voltage gets reduced in stages by STEP DOWN transformers nearer the user.

Types Of TransformerTypes Of Transformer

S tep U p S tep D ow n

Iso la ted

S tep U p S tep D ow n

A u tom otive

Tran s fo rm er

•What are power problems ?

•How do they affect working of computers ?

•What are the ways to cure them ?

Black Out Brown Outs- (dips) Spikes Sags Surges Line noise Continuous Low and High Voltages

BLACK OUTSBLACK OUTS* Implies total power failure

Cause : Excessive demand on the power grid, snapping of power cables, load shedding by electricity supply

boards.

Effects :* Loss of data stored on the hard drives due to sudden switching

off of the computer systems.

* Loss of work due to non functioning of Computers.

* Frequent corruption in Operating system and application soft- wares which need to be loaded again and again. Resulting in loss

of Many Man hours and delays in meeting deadlines.

BROWN OUTS/ DIPSBROWN OUTS/ DIPS

* Implies a significant drop in voltage .

* Cause :(i) Start up power demands of many electrical devices (Like motors, compressors, elevators etc).

(ii)Electric utilities lowering voltage levels to cope with extra ordinary power demands which are in excess of the

generating capacity.

* Effects : Possibilities of frozen keyboards and unexpected system crashes. Resulting in Hanged motherboards.

SURGESSURGES

* Implies a short term increase in voltage typically lasting 1/120th of a second.

*Cause : High powered electrical motors in air conditioners, house hold appliances etc. when switched off, causes

extra voltage to be dissipated through the power line.

*Effects: Delicate components can get stressed and this can cause system failure.

A/C

Elevator

TUBE-LITE

FANS

PCsMOTOR

SPIKESSPIKES* Implies an instantaneous increase in voltage of a very high

orders.

* Cause :Typically caused by a nearby lightning strike or by power lines being broken in a storm etc.

* Effect : Catastrophic damage to hardware. Loss of data`

Upto 2000

Transmission Line

GENERATION OF ELECTRIC

CONSUMER

LIGHTNING

Electric whatElectric what

LINE NOISELINE NOISE

* Implies Electro Magnetic Interference (EMI) & Radio Frequency Interference (RFI) in the line.

* Cause : Electrical noise is caused by lightning, load switching, generators, radio transmitters & industrial equipment.

* Effect : Noise introduces glitches & errors into executable programs and data files.

Types of Protection-Stabilizers

- Servo Stabilizers - Spikebusters

- CVTs- UPS Systems

SERVO STABILIZERSSERVO STABILIZERS

* Maintains a stable output in the presence of an erratic fluctuating input but has a slow response.

* It is not so suitable as the only protection device for computers because of their slow response and they are useless during a

power failure.

STABILIZERSSTABILIZERS

*It is a machine which gives stabilize /regulated output for a particular input range.Operation is achieved by the help of auto transformer and

electromechanical relays.

SPIKEBUSTERSSPIKEBUSTERS

* It reduce the severity of voltage spikes on the mains line.

* But they can neither provide a regulated output nor provide power in the event of a power failure.

CVTsCVTs

* It produce a very stable out-put voltage.

* It can remove voltage sags & surges from the mains voltage quite effectively.

* But CVTs are expensive and noisy.

* They are useless in the event of a power failure.

UPS SYSTEMSUPS SYSTEMS

* Protect the computer & other power sensitive equipments incase of power failure.

* Ensures a regulated stable output and additional filtering during spikes and surges.

Off-lineOn-line

Line-Interactive UPS

• Off-Line DATEX UPS systems have a battery power conversion circuit with a switch that senses power irregularities and automatically switches to battery.

• The main drawbacks of offline UPSs are that they offer only limited regulation and have a comparatively larger switchover time.

Charger Battery

Off-Line

AC InputAC Input

ACOutput

ACOutput

AC AC DC DC

AC AC DC DC

• In Datex Online UPS system, even in the presence of mains, the computer is always powered by the battery/inverter circuit.

• Another charger circuit keeps charging the battery.

• There’s no switchover involved.

• Online are more complex, bulkier and more expensive but offer a better Voltage regulation and pure sine wave output.

By Pass Switch

Battery

On-Line

ACOutput

ACOutputAC AC DC DC

DC

ACACInputAC

Input

• Similar to the offline units, Datex UPSs also switch to battery whenever input voltage hits predetermined levels.

• Line-interactive models provide voltage regulation features and have lesser switchover time and better performance than the offline models.

• They provide better protection against spikes and switching transients.

Regulator

Battery

Line Interactive

AC InputAC Input

Buck/Boost Buck/Boost

ACOutput

ACOutput

DC

AC

Discharge Charge

COMPARISON BETWEEN LINE INTERACTIVE AND ONLINE UPS SYSTEM

FEATURES

LINE INTERACTIVE

UPS

ON LINE UPS REMARKS

COST ECONOMICAL EXPENSIVE LI is more economical ascompared to Online ups.

VOLTAGEREGULATION

ADEQUATE

(220 10%)

EXCELLENT

(220 2%)

Online’s voltage regulation ismuch superior than LI.

TRANSIENTRESPONSE

O.K EXCELLENT LI takes typically 20 to 50 ms tocorrect a voltage and also someamount of transition alwayspassed on the load. But onlineUPS output is completely isolatedfrom input hence, no transient iscarried to the load.

WAVE FORM

QUASI SINEWAVE(MOSTLY)

PURE SINEWAVE There are some voltage sensitivedevices which require pure sinewave which can be only providedby online ups.

TRANSFER TIME

5 –10 Millisecond ZERO Online ups provides purelyuninterrupted and regulatedsupply to the load.

SERVICEABILITY

EASY TO SERVICE LITTLE DIFFICULT TOSERVICE

Because of compact size andsimple design LI is easy to serviceand replace as and when requiredand online is little difficult toservice bcz of its complicateddesign.

SIZE

COMPACT BULKY LI is small and relatively moreuser-friendly.

Comparison on the basis of costComparison on the basis of cost

Line-Interactive On-Line Remarks

Economical Expensive LI is more economical ascompared to Online UPS.

Comparison on the basis of Voltage Comparison on the basis of Voltage Regulation.Regulation.

Line-Interactive On-Line Remarks

Adequate Excellent Online’s voltageregulation is

much superiorthan LI.

Comparison on the basis of Comparison on the basis of Transient ResponseTransient Response

Line-Interactive On-Line Remarks

O.K Excellent LI takes typically 20to 50ms to correct a

voltage and also someamount of transition isalways passed on theload .But Online UPSoutput is completelyisolated from input

hence ,no transition iscarried to the load

Comparison on the basis of Wave Comparison on the basis of Wave FormForm

Line-Interactive On-Line Remarks

Quasi Sine wave(Mostly)

Pure Sinewave There are somevoltage sensitive

devices whichrequire pure sine

wave,which can beonly provided by

On-Line UPS.

Comparison on the basis of Transfer Comparison on the basis of Transfer TimeTime

Line-Interactive On-Line Remarks

5-10 Millisecond Zero Online UPS providespurely uninterruptedand regulated supply

to the load.

Comparison on the basis of Comparison on the basis of ServiceabilityServiceability

Line-Interactive On-Line Remarks

Easy to Service Littledifficult to

Service

Because of compactsize and simple

design LI is easy toservice and replace

as and whenrequired and onlineis little difficult toservice because of

its complicateddesign.

Comparison on the basis of SizeComparison on the basis of Size

Line-Interactive On-Line Remarks

Compact Bulky LI is small andrelatively more user-

friendly.

Comparison on the basis of WeightComparison on the basis of Weight

Line-Interactive On-Line Remarks

Light Heavy LI occupiesless space and

can beconveniently

moved around.

Comparison on the basis of Comparison on the basis of CapacityCapacity

Line-Interactive On-Line Remarks

Maximum Ratingupto 3KVA

Any rating Customer getswider choice inOn-Line UPSsystem.

Rating (VA & Watt)Transfer Time

Input Voltage WindowAVR (Voltage Regulation)

Backup TimeCrest Factor

Transient response

UPS RATINGUPS RATING

VA = V x I (volt ampere)Watts = V x I x Power factor

(watts is the actual energy consumed per unit time by an electrical load)

Power factor = Cosø(the ratio of actual power to reactive power is called power factor)

(For Datex Accure power factor is 0.8/>4.0)

(For Datex Clarrion power factor is 0.7 to unity)

TRANSFER TIMETRANSFER TIME

Switch over time in case of power failure from mains mode to the battery mode.

(For Datex Accure it is typically 2-3msec.)

(For Datex Clarrion it is Zero as in this case there is no transfer time.)

.

INPUT VOLTAGE WINDOWINPUT VOLTAGE WINDOW

Input voltage range within which the UPS continues to be in the mains mode.

(For Datex Accure input voltage window is 150-270 V )

(For Datex Clarrion input voltage window is 160-280 V)

AVRAVR (Automatic Voltage Regulation)(Automatic Voltage Regulation)

This is a feature which provides a regulated output voltage to the load & protects the load from voltage fluctuations.

(Datex Accure regulates output voltage within 220V ± 8%)

(Datex Clarrion regulates output voltage within 220V ± 1%)

BACKUP TIMEBACKUP TIME

The time period for which the UPS can supply power to the recommended load in the battery

mode is known as backup time.

CREST FACTORCREST FACTOR

It is defined as the ratio of Peak power load to average power load.

In case of DATEX it is >3

TRANSIENT RESPONSETRANSIENT RESPONSE

It is a sudden fluctuation in voltage lasting from 100th of a second to few seconds.

(In case of Datex Accure it is 20 to 50 ms).

(In case of Datex Clariion it is zero).

Battery Fundamentals

THE AUTOMOTIVE BATTERY

A lead-acid storage battery is an electrochemical device that produces voltage and delivers electrical current. The battery is the primary

"source" of electrical energy used in vehicles today. It's important to remember that a battery does not store electricity, but rather it stores

a series of chemicals, and through a chemical process electricity is produced. Basically, two different types of lead in an acid mixture

react to produce an electrical pressure called voltage. This electrochemical reaction changes chemical energy to electrical energy

and is the basis for all automotive batteries

Battery Basics

CELL VOLTAGE

Each cell element of the battery produces approximately 2.1 volts, regardless of the quantity or size of the plates. Automobile batteries have six cells that are connected in series, which produces a total

voltage of 12.6 volts.

BATTERYBATTERY

Specifications:-(1) Voltage 12V 6V & 2V Cells

(2) Ampere Hour (AH)

BATTERY CHARACTERSTICS

TYPES OF BATTERIES

-Ni Cd Batteries-Lead Acid

Ni Cd Batteries

Used for low power applications like, mobile phone, cordless phones etc.

Lead Acid Batteries

Used for high power applications, like UPS, Telephone exchange, Automobiles.

There are two types of Lead Acid Batteries -Sealed Maintenance free (SMF)

-Automotive

DIFFERENT BATTERIES GENERALLY IN USE

-12V 7AH-12V 17AH-12V 28AH-12V 45AH-12V 65AH

-Automotive 150Ah (trucking battery) exide.

Lead Acid Ni cd

High Power

Choice for UPS Low Power

Automotive

TYPES OF BATTERIES

Sealed Maintenance

free (SMF)