## What is LPF type wattmeter?

LPF wattmeter is used to measure power in inductive circuits. Inductive circuits have the property of lagging power factor and hence these wattmeters are used. Resistive circuits have unity power factor hence UPF wattmeters are used to measure power in these circuits.

Phantom Loading is a loading condition in which an energy meter is connected to factious or phantom load for testing of energy meter with high current rating. Such loading is favorable to avoid wastage of energy during the test of measurement instrument.

Direct loading requires rated voltage and current and so power is large. Testing at various power factor is also easy in phantom loading . It requires only a phase shifting transformer to shift phase of voltage w r t to current. No elaborate loading arrangement for various power factor is required.

### What is LPF power factor?

A low power factor (LPF) wattmeter is an instrument used to measure power in low power factor circuits. This type of wattmeters is employed for power measurement in circuits whose power factor is less than 0.5.

Why LPF wattmeter is used in load test?

In open circuit test the secondary winding of transformer is kept open . As the secondary side is open, the entire coil will be purely inductive in nature . So the power will be lagging due to inductive property of the circuit. So LPF (Low Power Factor) Wattmeter is used in OPEN CIRCUIT TEST of Transformer.

Which is true for a low power factor wattmeter?

Explanation: In a low power factor dynamometer type wattmeter, pressure coil has a resistance value that is one tenth of the actual with respect to unity power wattmeters. This is done in order to ensure a reasonable amount of torque at low power factors.

#### What is an example of phantom load?

Common examples of appliances and devices that have phantom loads include televisions, DVD players, cable boxes, stereos, coffee makers, microwave ovens, toasters, laptop chargers, hair dryers, and cell phone chargers. All of these devices consume energy, even while they are in the “off” mode.

What is the meaning of phantom load?

Have you ever heard of the term, “phantom load”? This term is used to describe any appliance or electronic that still uses electricity or “standby power” when turned off.

Why LPF wattmeter is used in no load test?

## Why do we use a low power factor wattmeter in magnetic circuit?

Definition: The instrument that measures the low value of power factor accurately is known as the Low Power Factor Wattmeter (LPFW). The low power factor meter is used for measuring the power of the highly inductive circuit.

Why is SC test carried by Energising HV side?

SC test is conducted on HV side and the measuring instruments are also placed in the HV side & the LV side is shorted. The main reason for performing the SC test on the HV side is that the rated current will be low in HV side when compared to the rated current in LV side.

How do you reduce phantom loads?

The easiest thing you can do to reduce phantom power is unplug anything you’re not using. This includes unplugging your phone or laptop charger when your device isn’t charging, not simply unhooking the device. Leaving cords plugged in when they’re not connected to anything is a common way phantom power can add up.

### Why no load current and no load power factor is low?

At no load, an induction motor draws a large magnetizing current and a small active component to meet the no-load losses. Therefore, the induction motor takes a high no-load current lagging the applied voltage by a large angle. Hence the power factor of an induction motor on no load is low.

Why UPF wattmeter is used in SC test of transformer?

In short circuit test the secondary winding of transformer is short circuited. As secondary side is short circuited the entire coil will be purely resistive in nature. So the power factor will be unity. So UPF(Unit Power Factor) Wattmeter is used in SHORT CIRCUIT TEST of Transformer.

Is phantom power AC or DC?

DC
Phantom power, in the context of professional audio equipment, is DC electric power transmitted through microphone cables to operate microphones that contain active electronic circuitry. It is best known as a convenient power source for condenser microphones, though many active direct boxes also use it.

The phantom loading mainly occurs in the “electronic” appliances. The phantom loading is used for examining the current rating ability of the energy meter. The actual loading arrangement will waste a lot of power. The phantom loading consumes very less power as compared to real loading, and because of this reason, it is used for testing the meter.