electrialstandards

Variable Refrigerant Flow (VRF) Systems Variable refrigerant flow type Air conditioners also known as Variable Flow Volume i.e. VRV, Where variable refrigerant means the ability of the system to control the amount of refrigerant flowing to multiple evaporators i.e. indoor units. Actually VRV consists of multiple Indoor units and all are connected to one single outdoor unit. VRV also provide the individual settings of all Indoor units and it can handle both heating and cooling in different zones simultaneously. VRV were originally manufactured by Diakin, Japan. These are more widely used for Industrial applications where ducting isn’t possible.  There is one problem that Design of VRF systems is more complicated and requires additional work compared to designing a conventional direct expansion (DX) system. Let’s how VRV is different from other Air conditioning systems:- Split Air-conditioning Split type air conditioning you have often seen which consists of one indoor unit along wit...

This circuit is a FM transmitter. can run it by 9v battery. the power consumption is very low about 10mA so a small 9v battery worked for long time. The frequency of radio must set between 88 to 93 MHz. The circuit contain trimmer for set frequency of transmitter. Part list: Transistor BC547(2pcs) Capacitor 10uF(2pcs) Capacitor 1nF(2pcs) Capacitor  5.6pF Trimmer 2-18pF Electret microphone Resistor 4.7k(3pcs) Resistor 100k Resistor 10k Resistor 270 ohm Coil 4mm diameter 5 turns air-core (2pcs) Antenna 10cm  

Technical Specification of Aluminum Cables in terms of codes So many times you have seen coding while specifying cables technical such as A2XWY now what does this means. Now there is nomenclature for the same which is used while describing the same. Where A -  Aluminium 2X- XLPE Insulation W – Steel round wire armour F- Steel Strip Armour WW- Double Steel round Armour FF- Double Steel Strip Armour Y- PVC outer Sheath Wa- Non Magnetic round wire Armour Fa- Non Magnetic Strip Armour AW- Aluminum Wire Armour Now As per A2XWY – This describes that it is Aluminum cable, XLPE insulated, With Steel round wire armour and having PVC outer Sheath. This coding is as per IS 7098(Part1):1988. You have also seen that there is coding for copper so there is no coding required in case of copper cables. XLPE cables advantages over PVC cables/ Thermoplastic cables:- 1.       XLPE cables have higher Power rating about 1.2 times PVC cables 2.       XLP...

This circuit is an one axis solar tracker. Today this circuit used in modern solar street light and solar systems in homes for increasing the efficiency. I tested it and work well. Best dc motor for this circuit is cordless drill motor (without removing gearbox)because that is very powerful and can move your heavy solar panel easily. In following video you can see how it work, however i test it without solar panel. Parts list: IC LM324 LDR(2pcs) Transistor BD139(2pcs) Transistor BD140(2pcs) Potentiometer 100k potentiometer 10k Diode 1N4007(4pcs) Capacitor 100n Resistor 47k Resistor 15k DC Motor 6 to 12v  

In Diesel generator there is Diesel engine which acts as a primary mover, Diesel engine drives an alternator to produce the electricity. In diesel engine air is compressed to a high ratio ranging from 14:1 to 25:1. During this compression, the air is heated to a temperature of 700–900°C. Depending upon the requirement quantity of diesel fuel is then injected into the cylinder, which ignites spontaneously because of the high temperature. That is why diesel engine is also known as compression ignition engine. DG has two types 1.       Two stroke and 2.       Four stroke. Mostly engines use the four stroke cycle. Here below is the working principle of four stroke engine. Four Stroke - Diesel Engine There are 4 stroke as below which takes place in Diesel Engine: (a)     Induction stroke (b)    Compression stroke (c)     Ignition & Power Stroke (d)    Exhaust stroke. Induction stroke Inl...

In all electrical measurements and protection purposes Current transformers and Voltage transformers are used. You can’t measure current upto 100A by directly connecting to Ammeter as Ammeter required for that purposes will be very much large in size which could not be installed. So CT’s are used for that purposes as CT will feed the current to Ammeter or any other measurement devices within limits of that measurement equipment. Same is the case of relays , relays can’t handle very high value of current and voltages. CT and PT are used for these purposed as these make current and voltages within limits of relay. CT and VT function like ‘ears' and the ‘eyes' of the protection system. Relay processes these signals and accordingly give commands to circuit breakers and other protection systems. Classification of CTs The CTs can be classified into following types: 1.     Measurement CTs 2.     Protection CTs A measurement grade CT has much lower VA capacity tha...

This circuit is a high voltage PWM dimmer for DC load. it can be very useful because most dimmers that available in markets are 12 to 24v. I tested it by 33v(because my power supply can't give more voltage)  but it can work by up to 50v DC. R2 can be 1k to 1.5k. Parts list: IC 555 N-Channel MOSFET such as IRFZ44 Diode 1N4148 Zener diode 10v 1W Potentiometer 50k Capacitor 0.1uF Resistor 1k(2pcs) As you can see in following fig. there are some parallel horizontal lines in image when you see to a PWM LED from an camera because it flashing with very high speed, that also occur when you want to take a picture from CRT TV display.

PWM today used in many areas such as solar charger, motor speed controller, light dimmer, mobile battery charger, etc. Following circuit is a PWM light dimmer that used IC 555. By this circuit you can change the brightness of LED lights. It also help to decreasing power consumption because when the LED is ON in fact it flashing by very high speed but the humans eye can not identifies that so we will see it continuous shine.  

FIXED CAPACITOR Fixed capacitor is the capacitor in which capacitor value remains fixed. In these capacitor capacitance cannot be adjusted. A fixed capacitor is classified according to the type of material used as its dielectric, such as paper, oil, mica, or electrolyte. These types of capacitors are discussed in earlier post. VARIABLE CAPACITOR As clear from its name variable capacitor is one where A variable capacitor is constructed in such manner that its value of capacitance can be varied. A variable capacitor is similar to motor having rotor & Stator. It consists of two sets of metal plates arranged so that the rotor plates move between the stator plates. Air acts as dielectric in these capacitors. As the position of the rotor is changed, the capacitance value is likewise changed. à This type of capacitor is used for tuning most radio receivers. Its physical appearance and its symbol are shown in figure below. Another capacitor consists of two pl...

Types of Capacitors:- Capacitors are classified according to type of material used as its dielectric, such as paper, oil, mica, or electrolyte. (A)     PAPER CAPACITOR That kind of capacitor is made of flat thin strips of metal foil conductors that are separated by waxed paper.    à Range is 300 picofarads -4 microfarads. è Voltage =600 volts. In these capacitors, Capacitors are sealed with wax to prevent the harmful effects of moisture and to prevent corrosion and leakage. There are so many outer covering used in paper capacitors out of these simplest being a tubular cardboard covering. Some types of paper capacitors are encased in very hard plastic. These types are very rugged and can be used over a much wider temperature range than can the tubular cardboard type. (B)     MICA CAPACITOR These type of capacitors are made of metal foil plates that are separated by sheets of mica. Mica is used as Dielectric medium.   The whole assembly is en...