Precautions When using Ammeter – Must Follow procedure

PRECAUTIONS WHEN USING A VOLTMETER & AMMETERS

  • Observe the correct polarity.
  • Wrong polarity causes the meter to deflect against the mechanical stop and this may damage the pointer.
  • Place the voltmeter across the circuit or component whose voltage is to be measured.
  • When using a multi range voltmeter, always use the highest voltage range and then decrease the range until a good up-scale reading is obtained.
  • Always be aware of the loading effect.
  • The effect can be minimized by using as high a voltage range as possible. The precision of measurement decreases if the indication is at the end of the scale.

ammeter1
 Probable Causes- 

  1. Discontinuity in measurement terminals,
  2. selector switch,
  3. attenuator or the shunt; or
  4. A fault PMMCC movement.

PRECAUTIONS WHILE USING AN AMMETER

  • Never connect an Ammter across a source of emf.
  • Because of its low resistance it would draw damaging high current and destroy the delicate movement.
  • Always connect an ammeter in series with a load capable of limiting the current.
  • Observe the correct polarity.
  • Reverse polarity causes the meter to deflect against the mechanical stop and this may damage the pointer.
  • When using a multi range meter, first use the highest current range, the decrease the current rage until substantial deflection is obtained.
  • To increase accuracy of the observation, use the range that will give a reading as near to full-scale as possible.

       Probable causes-

  • Faulty circuit,
  • Open load,
  • High resistances,
  • Open connections of shorts meter terminals.
Comments(2)
  1. keneilwe February 6, 2016
  2. thabang sello March 25, 2016

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