Controller method for automatic voltage regulator

20/08/2011 by 3 Comments

Basically automatic voltage regulator for generator have a 2 mode selection.It is with full automatic function and manual function.

I already discuss about AVR function and basic operation in my last post.Please refer to basic of automatic voltage regulator.i hope it can make a clear view and understanding about AVR function in generator.

This time i want share some information about controller method that commonly used for AVR for generator.For latest design of AVR,manufacture put a two(2) selection for AVR controller mode.It is Automatic and Manual mode. read more

Filed Under: Generator Tagged With: , , , , , ,

UPS battery charger

17/05/2011 by 6 Comments

When indicator for batteries level shown a it  need to recharge,We must charge the batteries to ensure it in full capacity and can operate during power failure.But for UPS batteries charger it typically build in the UPS system.

Now in market,it have several battery charger technology for AC and DC UPS.Basically it similar with car battery charger.The method and technique similar with conventional charger.

Manufacture always improved and made R&D to created battery charger more efficient,safety and durability for user.They design with electronic device for more accurate and faster charging system. The advanced technology usually design for batteries charger included with several items below :- read more

Filed Under: Theory Tagged With: , , , , , , ,

Battery for UPS

16/05/2011 by Leave a Comment

For uninterrupted power supply ( UPS ),the important component is a battery unit for UPS.The battery are used to store DC energy which is later used to supply a block of energy to a load,often in the form of a high current for a short time example to charge mechanism springs in switch gear,fire fighting system,emergency lighting, emergency instrumentation power for control panels and control devices and starter motors on engines generator.

Battery for UPS  must in good condition and well maintain to ensure it can operating in full capacity when it needed.If the battery failure during interruption of power supply,it can cause serious damage and high cost for operation recovery.

Types of battery

Normally for industry used applications are invariable of two kinds of battery,It have a advantage and disadvantage depend on our application :

1) Lead-acid (Pb).

2) Nickel-cadmium (NiCd).

A battery consists of a number of cells connected in series. The series connection is necessary to create sufficient load voltage. Each cell has a low voltage which is peculiar to the type of cell and independent of the current and rating of the cell. The cell voltages are shown in Table 17.1.

 

How to recharge the batteries for UPS?

The maximum cell voltages during charging should not exceed 2.7 volts per cell for Pb cells and 1.85 volts per cell for NiCd cells.Suppose a nominal voltage of 110 DC is required then at least 54 Pb cells or 89 NiCd cells would be required.The size of a battery is defined as its ampere-hour capacity, since capacity is related to charge (Q) which equals current (I ) × time (T ).

 

If there is a total failure from the main supply then it will usually be necessary to maintain the continuous current for 4 hours so that the state of the plant will be known during the failure. During this time it would be expected that the main supply would be restored.

Hence the 4 hours can be used as the operating cycle of the battery in the event that the charger is unable to supply current.

For the battery storage and compartment it may be installed in several ways.Example it can install integral with the charger, in a separate cubicle or on open racks.

The choice usually depends upon the physical size of the complete battery.If we plan to used a large battery,it are more suited to an open rack installation.

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Automatic voltage regulator for generator

03/04/2011 by 34 Comments

The AVR ( automatic voltage regulator ) is suitable for supplying power to the fields of either brushless or commutator type exciters and will maintain the A.C generator voltage within plus and minus 1% of the preset value with paralleling.

When the load varies between no load and rated load and with a frequency changes more than plus minus 4%.Upon application or rejection of rated load,the generator voltage recovers to plus and minus 1% within 0.3 second on most AVR exciter in A.C generator combination. read more

Filed Under: Generator Tagged With: , , , , , , ,

Generators in parallel

27/03/2011 by 1 Comment

When generators are operated in parallel condition,it necessary to be arrange for both real power ( kW ) and reactive load ( kVar ) sharing in proportion to their standard rating.Real load output from generator determined by torque applied to the shaft and this can only be controlled by controlling the prime mover driving the generator.

Reactive load is a function of generator excitation.Under parallel operation,adjustment to field excitation does not affect to output voltage.In general,an under-excited machine will generate at a more lagging power factor current.

The three phase sensing regulator operates in similar manner except that the voltage across the reactor carrying a current proportion to one phase current is added to the voltage of that phase. read more

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Types Of Earthing Systems

23/02/2011 by 36 Comments

Last post i already discuss about Earthing system classification.I mention earthing system have a several types such as TT,IT,TN-C,TN-S and TN-C-S.This time i want explain detail about type of earthing systems.

Earthing system is designed followed by electrical system required and the application.It have different earthing system for each electrical application such as consumer power supply,substation,offshore,ships,underground system,generator and over head system.

We must know the suitable earthing types to ensure our system is fully protected and safety.I explains detail about all of five ( 5 ) earthing system types below.I hope it can help to understand about earthing system. read more

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Rectifier

25/01/2011 by 1 Comment

This device is typical in control panel or automation industry.The main purpose of RECTIFIER is to convert from  AC ( alternating current ) to DC ( direct current ).It common use because now in market,all control device is using DC power supply.It safe and energy efficiency.

Usually when we choose to control our machine or equipment using PLC or Electronic Device,We need DC ( direct Current ) power supply.The range common use in world wide is from 12 VDC until 24 VDC.So we use the RECTIFIER to convert from 110 VAC or 240VAC power supply to DC power supply :D

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Filed Under: Automation Tagged With: , , , , , , ,
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