What is Phantom Loading (Fictitious Loading) Definition Applications Example

 Phantom Loading is a method of testing energy meters (especially watt-hour meters) without applying full-load power to the meter.

It allows the meter to operate under rated voltage and current conditions, but with very little power consumption from the supply.

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🔹 Why Phantom Loading is Needed

When testing an energy meter directly (called Direct Loading):

• Full load current and rated voltage must be supplied.

• This requires large power, especially for high-capacity meters.

• Most of the power is wasted as heat in the load resistors.

👉 To avoid this wastage, Phantom Loading is used.

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     Normal Supply (230V)

         │

         │

      Pressure Coil (Voltage Coil)

         │

         └───────────────┐

                         │

   Low Voltage Supply (6V or 12V) → Current Coil

                         │

                         └──────→ Neutral

🔹 Power Consumption Comparison

Let:

• Voltage = 230 V

• Current = 20 A

• Power Factor = 1

🔸 Direct Loading Power:

$P = VI = 230 × 20 = 4600 W$

🔸 Phantom Loading Power:

• Power in voltage coil circuit ≈ 230 V × small current (say 0.1 A) = 23 W

• Power in current coil circuit ≈ 6 V × 20 A = 120 W
  ✅ Total Power = 23 W + 120 W = 143 W only

Hence, huge power saving.

🔹 Principle:

In Phantom Loading,
the voltage and current circuits of the meter are energized separately from two different supplies.

• The voltage coil (pressure coil) is connected to a normal voltage supply (e.g., 230 V).

• The current coil is connected to a low-voltage, high-current supply (e.g., 6 V or 12 V).

Thus, the meter receives the correct current and voltage proportion, but the actual power taken from supply is very low.

🔹 Advantages

✅ Very small power required for testing.
✅ Economical for large capacity meters.
✅ Easy to vary current and voltage independently.
✅ No overheating or power wastage in test load.

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🔹 Disadvantages

❌ Requires two separate supplies (AC for voltage coil, low-voltage for current coil).
❌ More complex setup.
❌ Only suitable for laboratory testing — not for field testing.

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🔹 Applications

• Used for testing single-phase and three-phase energy meters in labs.

• Used to calibrate meters without applying actual heavy load.

• Common in meter testing benches at utilities and manufacturers.

🔹 Example Question (MCQ)-

Q. Why is phantom loading used for testing energy meters?
A. To test meters at rated load current and voltage with minimum power consumption. ✅

Q. In phantom loading, voltage coil is supplied from —
(a) Low-voltage source
(b) High-voltage source
(c) DC source
(d) None of these
Answer: (b) High-voltage source (rated supply voltage)

Q. The current coil in phantom loading is energized by —
Answer: A low-voltage, high-current AC supply.