Types of Electrical Testing Equipment Instruments Uses and Its Definition

Meter Testing Instrument in the field of electrical engineering or in electronics engineering is so importantwithout those instrument you cannot repair or analyze the system or equipmnent or even design a new one. As I googling  on the Net I discovered that huge of instrument testing for as to know as an electrical engineer. Like Cable-Length Meters, Electric Tachometer, Electrical Thermometers, Footcandle Meter, Frequency Meter, Miscellaneous Testing Instruments and many others.

Cable-Length Meters
Cable-length meters measure the length and condition of a cable by sending a signal down the cable and
then reading the signal that is reflected back. These instruments are also called time-domain reflectometers
TDRs. A similar instrument used to measure the length of fiber optic cables is called an optical timedomain
reflectometer ODTR.

Electric Tachometer
This consists of a small generator that is belted or geared to the equipment whose speed is to be measured.
The voltage produced in the generator varies directly with the rotational speed of the generator.
Since this speed is directly proportional to the speed of the machine under test, the amount of the generated
voltage is a measure of the speed.

Electrical Thermometers
For the measurement of temperatures, there are three basic types of electrical thermometers.Resistance thermometers operate on the principle that the resistance of a metal varies in direct proportion to its temperature. They are normally used for temperatures up to approximately 1500°F.Thermocouples operate on the principle that a difference in temperature in different metals generates a voltage, and are used for measuring temperatures up to about 3000°F. Radiation pyrometers and optical pyrometers are generally used for temperatures above 3000°F. They combine the principle of the thermocouple with the effect of radiation of heat and light.

Footcandle Meter
A footcandle meter consists of a photosensitive element and a meter that indicates the average illumination of a room or other space in footcandles. Typical footcandle meters can read light intensity from 1 to
500 footcandles or more. To use the footcandle meter, first remove the cover. Hold the meter in a position so the cell is facing toward the light source and at the level of the work plane where the illumination is required. The shadow of your body should not be allowed to fall on the cell during tests. A number of such tests at various points in a room or area will give the average illumination level in footcandles. Readings are taken directly from the meter scale.

Frequency Meter
Frequency is the number of cycles completed each second by a given AC voltage, usually expressed in
hertz ; 1 Hz = 1 cycle per second. The frequency meter is used with AC powerproducing devices like generators to ensure that the correct frequency is being produced. Failure to produce  the correct frequency can result in overheating and component damage.

Miscellaneous Testing Instruments
Ammeters, voltmeters, and megohmmeters are the most common analog devices used for field testing
and troubleshooting applications. However, several other specialized types of test instruments should be mentioned briefly.

Power Factor Meter
Power factor is the ratio of the true power,voltamperes to apparent power,watts, and it depends on the phase difference between current and voltage. Three-phase power factor meters are installed in
switchboards. Many utilities charge large commercial and industrial users a penalty if power factor falls
below 90 percent; so these users try to maintain high power factor at all times. A high power factor provides better voltage regulation and stability.

Power Quality Analyzers
Power quality analyzers are portable test instruments similar in construction to the digital multimeters.
unlike DMMs, which typically measure only one property of electrical circuits at a time, power quality analyzers have dual probes that allow both voltage and current to be measured simultaneously. Power quality analyzers can also measure frequency and harmonics. The ability to measure Power quality analyzer display showing voltage on top, current on bottom, and time stamp at upper right. and display multiple circuit characteristics at the same time is useful in troubleshooting power quality problems in power distribution systems.

Photo Tachometer
This instrument aims a light at the rotating shaft on which there is a contrasting color such as a mark, a chalk line, or a light-reflective strip or tape. The rotational speed in rpm is read from an indicating scale. Photo tachometers are especially useful on relatively inaccessible rotational equipment such as motors,
fans, grinding wheels, and other similar machines where it is difficult, if not impossible, to make contact
with the rotational unit.

Phase-Sequence Indicator
A common phase-sequence indicator is designed for use in conjunction with any multimeter that can
measure AC voltage. Most can be used on circuits with line voltages up to 550 VAC, provided the instrument used with the indicator has a rating this high. To use the phase-sequence indicator, set the multimeter to the proper voltage range. This can be determined if it is not known by measuring the line voltage before connecting the phase-sequence indicator. Next, connect the two black leads of the indicator
to the voltage test leads of the meter. Connect the red, yellow, and black adapter leads to the circuit in
any order and check the meter for a voltage reading. If the meter reading is higher than the original circuit voltage measured, then the phase sequence is black-yellow-red. If the meter reading is lower than the original circuit voltage measured, then the phase sequence is red-yellow-black. If the reading is the
same as the first reading, then one phase is open.

Tachometers
A tachometer is a device that indicates or records the speed of rotating equipment (motors and generators) in revolutions per minute,rpm. There are several different types:

Vibrating-reed Tachometer
This instrument is simply held against the motor, turbine, pump, compressor, or other rotating equipment, and the speed is shown by the vibration of a steel reed, which is tuned to a certain standard
speed.