Transformer rating

Transformer rating or capacity depend on the  limited of insulation temperature can stand for maximum load.The ratings can be up or down when we reducing a  core and copper losses.

To reduce core and cooper losses,we can improved the rate of heat exchange with proper cooling system or by improving quality transformer insulation that can stand for high temperature.

For larger transformer types,we can remove more heat with increased area for efficient cooling and increased volume of oil to absorb more heat to reduce the temperature. read more

Auto transformer

This is a one from several types of transformer.It usually used for motor starter,we recognize it by name “auto transformer starter”.Basically design for auto transformer only have a single winding and provided with tap connection for step up or down.

It have magnetic core with single winding which common primary and secondary circuits.The primary connection is connected with main AC power supply and secondary connection is connected with load.

If the primary is the total winding and is connected to a supply and the secondary circuit is connected across only a portion of the winding,It mean this is for stepped down voltage. read more

UPS batteries charging rates

Basically charging rates for UPS batteries depend on type of batteries cell such as Lead-acid (Pb) or Nickel Cadmium (NiCd).This two types of batteries cell have a different method to charging up.

For Lead-acid (Pb) cells is used a ‘constant voltage’ method.It mean where the current varies as the state of charge changes.Different method for Nickel Cadmium (NiCd) cells,it  is used ‘constant current’ where the cell voltage varies as the state of charge changes.

When we try to charging batteries  from  Lead-acid (Pb) cells type,the basic process are from a constant voltage source the charging current starts high and slowly decreases to a constant value when the cells become fully charged.The constancy of the current is an approximate indication that the cells are fully charged. read more

UPS battery charger

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

Battery for UPS

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.

Benefits of power factor correction

Now around the world,hot topic is about energy saving and energy efficiency.The main item very popular for discussion is how to reduce electricity bills.

In industrial sector,the first step to reduce electricity bills is a power factor correction.This post i explain about the benefits of power factor correction for energy saving and efficiency.It also common practice for industrial.

I already discuss in my last post about power factor correction and capacitor sizing for power factor correction.If you understand the concept and how to calculated the capacitor sizing,you also can do it your self for power factor improvement. read more

Capacitor sizing for power factor correction

Commonly method for power factor correction using the capacitor to generate reactive power ( kVAR ) to reduce apparent power ( kVA ) form inductive load.

This time i want share a simple method to sizing our capacitor to improve power factor for induction motor and utility electricity.This method also can use for capacitor bank sizing.

Power factor correction is the one of famous topic for all electrical person at around the world.Many discussion and debate about how to sizing the capacitor for power factor correction.

How to sizing capacitor for power factor correction?

To properly sizing the amount of capacitor (kVAR) required to correct the lagging power factor,we  must have three (3)  important of information below: read more