What will happen when power factor is leading in the distribution of power?

If there is a high power factor, i.e if the power factor is close to one:

1. Losses in the form of heat will be reduced;
2. The cable becomes less bulky and easier to carry, and very cheap to afford, &
3. It also reduces over heating of transformers.

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What are the functions of Protective Relays?

Figure: Protective Relaying System

Functions of Protective Relays:

• To detect the faults. For Example: Short circuits.
• To detect abnormal operating conditions. For example: Overloads, unbalances, low voltage or frequency.
• To Initiate the operation of the circuit breaker to isolate the defective element from the rest of the system, thereby protecting the system from damages consequent to the fault.
• To Control and supervision. For example: Automatic reclosing, bus transfer, synch-check.

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List of Acronyms on Digital Electronics

ACRONYMS ON DIGITAL ELECTRONICS:

ACDS —advanced   combat direction   system.

ACRO (or CRO) —auxiliary   cathode   readout.

ALT key —alternate   key.

A/N —alphanumeric.

APA —all points addressable.

AM —amplitude modulation.

ASCII   —American Standard Code for Information Interchange.

ASTAB —automated status board.

ASW —antisubmarine   warfare.

BC —broadcast.

BDU —basic display unit.

BER —bit error rate.

BITE —built-in test equipment.

BPS —bits per second.

C2P —Command and Control Processor.

CAG —central automated status board generator.

CCAEP —computer-controlled action entry panel.

CDB —central data buffer.

C-DITEG —common digital television graphics generator.

CDS —combat direction system.

CED —console electronic drawer.

CEG —central equipment group.

CGA —color graphics adapter.

CIGARS —console internally generated and refreshed symbols.

CIU —computer interface unit.

CONICS —circles and ellipses.

CP —clock pulse.

CPS —cycles per second.

CRO —TV monitor.

CRT —cathode-ray tube.

CTRL —control.

dB —decibels.

DCC —display control console.

DCI —direct computer interface.

DDEU —digital data entry unit.

DDI — (1) digital data indicator; (2) digital display indicator.

DITEG —digital television graphics generator.

DIV —diversity.

DLRP —Data Link Reference Point.

DMU —display multiplexer unit.

DRAC —digital radar azimuth converter.

DSC —digital scan converter.

DTS —data terminal set.

EDAC —error detection and correction.

EF word —external function word.

EGA —enhanced   graphics   adapter.

EMI/RFI —electromagnetic   interference/radio frequency interference.

EPROM —erasable, programmable read-only memory.

ESC key —escape key.

FM —frequency modulation.

GUI —graphic user interface.

HF —high frequency.

HVPS —high voltage power supply.

HZ —hertz.

I/O —input/output.

IFF/SIF —identification, friend or foe/selective identification feature.

JTIDS —Joint   Tactical   Information   Distribution System.

J-SERIES MESSAGE —The fixed format messages containing tactical data and commands that are used to exchange information over the JTIDS system.

JU —JTDS   Unit.

LCD —liquid crystal display.

LCLV —liquid crystal light valve.

LED indicator —light-emitting   diode   indicator.

LINK-4A —The tactical digital data link for controller-to-controlled aircraft communications.

INK-11—The tactical digital data link for communications among a multiple number of units.

LINK-16 —The tactical digital data link for communications   among a multiple number of units.  This link is a secure, jam resistant, nodeless, high-capacitlinky that uses the JTIDS terminal.

LSB —Lower Side Band.

LSD —large screen display.

VPS —low voltage power supply.

MDA —Monochrome   Display   Adapter.

M-SERIES MESSAGES —Link-11   messages.

NCS —Net Control Station.

NCT —Net Cycle Time.

NICP —Network   Interface   Control Program.

N-SERIES MESSAGES —The “normalized” messages exchanged between the C2P computer and the ADCS computer.

NTDS —naval tactical data system.

ODR —output data request.

OJT —on-the-job training.

OSC —operations summary console.

PA/SG —pulse  amplifier/symbol generator.

PC —personal computer.

PEFT —peripheral equipment functional test.

PIO —peripheral   I/O

PIXEL —picture element.

PMS —planned maintenance system.

POFA —programmed operations functional appraisal.

PPI —plan position indicator.

PPLI —precise participant location and identification.

PPU —projection plotting unit.

PROM —programmable read-only memory.

PU —participating unit.

RAC —radar azimuth converter.

RAM —random access memory.

RC —Roll Call.

RDDS —radar data distribution switchboard.

RELNAV —relative navigation.

RF —radio frequency.

RGB —red, blue, green.

ROM —read-only memory.

ROM BIOS —ready-only memory basic input output system.

R-SERIES MESSAGES —Link-4A messages from the controlled aircraft that are sent in response to a control message

SAC —sonar azimuth converter.

SCG —sensor converter group.

SDDS —sensor data distribution switchboard.

SG —symbol generator.

SRAC —synchro radar azimuth converter.

SVGA —super videographics array.

TDM —tactical   DITEG   module.

TDS —tactical data system.

TFT —thin film transistor.

TMG —test message generator.

TN —track   number.

TQ —track quality.

TSLO —third salvo lock out.

TTL —transistor-transistor logic.

TVC —television converter group.

TVSC —television scan converter.

UHF —ultra-high frequency.

USB —upper side band.

V/C word —velocity/category word.

VDT —video display terminal.

VFK panel —variable function key panel.

VGA —video graphics array.

V-SERIES MESSAGES —Link-4A control messages sent from the controlling station to the controlled aircraft.

VSS —video signals simulator.

XGA —extended graphics array.

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What are the Characteristics, Power Ranges and Applications of different types of AC & DC Motors?

Characteristics, Power Range and Applications of some AC & DC Motors:

Motor Types	Characteristics	Power Range	Applications
DC Motors
DC shunt motor	Constant flux constant speed motor creates moderate torque at start.	Up to 200 hp	Machine tools like lathes, milling machines, grinding machines, centrifugal and reciprocating pumps, blowers, and fans.
DC series motor	Creates dangerously high torques at low speeds and should be always connected to the load; speed can be varied.	Up to 200 hp	Preferred for traction-type loads; employed in electric locomotives, conveyors, cranes, elevators, trolleys.
Permanent magnet DC motor	Higher efficiency, smaller size and simpler architecture; magnets can become demagnetized due to excessive use and overheating; produces lower torque.	Up to 10 hp	Power windows in automobiles, computer peripherals.
Separately excited motors	Can be controlled either by varying the voltage applied to the field winding or by varying the voltage applied to the armature; can produce high torques.	Up to 100 hp	Traction applications, to control the speed and torque of the motor by changing both armature voltage and stator current.
AC Motors
Three-phase induction motor (Squirrel cage rotor)	Moderate starting torque. Simple robust and maintenance free construction. Speed control by addition of rotor resistance is not possible.	1–5000 hp	Lathe machines, water pumps, grinders, printing machines, large refrigeration and air-conditioning units, small compressors.
Three-phase induction motor (Slip ring rotor)	Very high starting torque. Speed control by rotor resistance possible. High cost. Complicated construction which requires maintenance due to use of slip rings and brush.	1–5000 hp	Cranes, hoists, elevators, large compressors, industrial fans and blowers.
Three-phase synchronous motor	Constant speed irrespective of load, need of a starting device, need for two different excitation sources, variable frequency drives required for speed control.	Up to 50,000 hp	Motor generator sets, timing devices, centrifugal pumps, textile mills, cement mills, rolling mills.
Special Types of Motors
Single-phase induction motor	Simple and rugged construction.	Up to 5 hp	Fans, water pumps, and refrigerators.
Stepper motor	Smooth rotation, linear relation between electrical input and step rotation.	Sub-fractional horsepower rating	Used for precise position control in printers, floppy disk drives, robotics, process control, machine tools.
Brushless DC motor	No maintenance required, long life, high reliability and efficiency, low inertia and friction, low starting torque and high costs, ability to run at speeds as high as 50,000 rpm.	Up to 300 hp	Video recorders, computer peripherals, biomedical instruments, commercial ovens, film processing equipment, printing technology, and material handling equipment.
Universal motor	High-power-to-weight ratio, can produce high starting torque, can operate at very high speeds, suits wide variety of applications demanding different torques, shorter lifespan.	Used exclusively in fractional horsepower range	Small appliances like mixers, blenders, drills, saws, vacuum cleaners, sewing machines.

Read more: Discuss Different types of Motors & their Uses.

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