The following points highlight the top seven instruments used for measuring the flow of current. The instruments are: 1. Ammeter 2. Voltmeter 3. Wattmeter 4. Ampere-Hour Meter 5. Watt-Hour Meter or Kilowatt-Hour Meter 6. Insulation Testing Megger or Megger Testing Set or Megger 7. Earth Testing Megger or Megger Earth Tester or Meg Earth Tester. Instrument # 1. Ammeter: The [...]
In this article we will discuss about the connection of an ammeter for measuring heavy current. When the line current is high, total current of the supply line cannot be sent through the coil of the ammeter. For carrying high current, the cross-section of the coil must be large, and it becomes very difficult to make coil of a conductor [...]
In this article we will discuss about the disadvantages of ampere-hour meters. Ampere-hour meter actually measures electrical energy in ampere-hour. It is equal to current in ampere flowing through the current coil of the meter multiplied by the time in hour during which the current flows. But as the B.O.T. unit of electrical energy is kilowatt-hour, the scale of the [...]
In this article we will discuss about the connection of voltmeters for the measurement of high voltages. If the supply voltage is high, the resistance of the coil alone may not be sufficient enough to prevent flow of heavy current through the voltmeter. In order that a short-circuit may not occur between the lines at the point of connection, the [...]
In this article we will discuss about the use of earth testing megger, explained with the help of an example. Earth testing megger has either three terminals or four terminals. The three terminals of the instrument are marked as E, P & C. In some instruments the word 'Earth' is used in place of E. The main earth electrode under [...]
In this article we will discuss about the commonly used D.C and A.C energy meters. 1. D.C. Energy Meters: (A) Ferranti Mercury Meter: It is a very commonly used energy meter of mercury ampere-hour type. The construction and connection of this meter are shown in fig. 68. Ferranti mercury meter consists of a disc revolving between two permanent magnets,—one acting [...]