Transducer is an element which converts one form of energy into another.

Active transducer and passive transducer.

Range, accuracy, repeatability and sensitivity.

Linear variable differential transformer and is a magnetic displacement transducer. The magnitude of voltage induced in secondary would be the indicative of the amount of displacement that had taken place.

It is an example of a resistance changing passive transducer. When the gauge is stretched or compressed, the resistance of the wire in the gauge changes.

An active transducer is a self-generating transducer which converts energy directly from one state to another without the need for an external power source or excitation.

A passive transducer is one which does not convert energy directly but derives the power required for energy conversion from an external source.

Active transducer: thermocouple, piezo electric crystals, photo voltaic cells

Passive transducer: potentiometer, resistance thermometer, strain gauge, photo conductive cell, thermistor, capacitor transducer, differential transformer and magnetic transducer.

The cables installed must comply with current ratings and voltage drop limitations’ passage of Current results in voltage drop along the length of the cables,’ hence voltage drop becomes A problem in very long -cables. Excessive Voltage drop can seriously affect the proper operation of electronic equipment. Motor can give starting problem if voltage drop at the starting current is excessive. The voltage drop in cables from the main switch board to the appliance must not Exceed 6% (in practice it is about 2%)

1. When several cables are run close together or are touching, the heat from one cable affects others, and thus requires lowering rating. For example, if more than 6 cables are running bunched together, it is usual to reduce the current ratings to 85%.
2. Where possible, cables intended for different operating temperatures should not be bunched In common clips, glands, conduits or pipes’

Under short circuit condition there is rapid rise in the conductor temperature, affecting cable Insulation. Mechanical forces due to magnetic effect and longitudinal expansion of conductors Due to heat have also to be considered. It is therefore necessary to match the cable size with the Short circuit protection equipment (fuses or circuit breakers) which may take certain time (a fraction of a second to several seconds) to trip.