Types of Secondary Instruments

Types of Secondary Instruments Points : Types of Secondary Instruments: The secondary instruments are further classified into following groups namely:
(i) Indicating Instruments.
(ii) Recording Instruments.
(iii) Integrating Instruments.
(iv) Displaying Instruments. Indicating Instruments: Indicating instruments are those which indicate the magnitude of an electrical quantity at the time when it is being measured. The indications are given by a pointer moving over a graduated dial. Ordinary ammeters, voltmeters, watt meters, frequency meters, power factor meters etc: fall into this class. Recording Instruments: These are those instruments which keep a continuous record of the various of the magnitude of an electrical quantity to he observed over a definite period of time. In such instruments the moving system carries an inked pen which touches lightly a sheet of paper rapped over a drum moving with uniform slow motion in a direction perpendicular to that of the deflection of the pointer. Thus a curve is traced which shows the variations in the magnitude of the electrical quantity under observation over a definite period of time. Such instruments are generally used in power houses where the current, voltage and power etc., are to be maintained within certain specified values. Integrating Instruments: Are those instruments which measure and register by a set of dials and pointers either the total quantity of electricity (in amp-hours) or the total amount of electrical energy (in watt hours or kWh) supplied to a circuit in a given time. This summation gives the product of time and the electrical quantity but gives no direct indication as to the rate at which the quantity or energy is being supplied because their registrations are independent of this rate provided the current flowing through the instrument is sufficient to operate it. Ampere — hour, watt hour and kWh meters fall in this class. Displaying Instruments: These are the instruments which measure the value of (voltage, time etc.) in the form of waves on the screen. For example oscilloscope.