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Verification of the phase sequence in a circuit is of considerable practical importance. A lamp or other indicator lights to show the sequence of voltages at the terminals for the given direction of shaft rotation. Phase sequence of two sources can be verified by measuring voltage between pairs of terminals and observing that terminals with very low voltage between them will have the same phase, whereas pairs that show a higher voltage are on different phases. Three-phase motors also vibrate less and hence last longer than single-phase motors of the same power used under the same conditions. Phase converters are used when three-phase equipment needs to be operated on a single-phase power source. Such converters may also allow the frequency to be varied, allowing speed control. The steam passes through pipes to a steam turbine and turns it at high speed. Fuses for commercial or industrial power systems must have higher interrupting ratings, with some low-voltage current-limiting high interrupting fuses rated for 300,000 amperes. A three-phase induction motor has a simple design, inherently high starting torque and high efficiency.

A rotary phase converter is a three-phase motor with special starting arrangements and power factor correction that produces balanced three-phase voltages. These voltages feed into either a wye- or delta-connected load. Examining the circuits, we can derive relationships between line voltage and current, and load voltage and current for wye- and delta-connected loads. Line frequency flicker in light is detrimental to high-speed cameras used in sports event broadcasting for slow-motion replays. Oscillatory motion of the physical line is termed conductor gallop or flutter depending on the frequency and amplitude of oscillation. In a balanced system each line will produce equal voltage magnitudes at phase angles equally spaced from each other. Capacitors and autotransformers can be used to approximate a three-phase system in a static phase converter, but the voltage and phase angle of the additional phase may only be useful for certain loads. Inductive and capacitive loads will cause current to either lag or lead the voltage.

With linear loads, the neutral only carries the current due to imbalance between the phases. The heating of short line conductors due to line losses sets a thermal limit. Alternatively, shutters may be opened by simultaneous insertion of line and neutral pins. This was set out as a formal strategic goal, which became known as the All Red Line. The motor-generator method can also form an uninterruptible power supply when used in conjunction with a large flywheel and a battery-powered DC motor; such a combination will deliver nearly constant power compared to the temporary frequency drop experienced with a standby generator set gives until the standby generator kicks in. The method of symmetrical components is used to analyze unbalanced systems. Other usual three-phase loads in the domestic field are tankless water heating systems and storage heaters. In the UK, transmission costs are about 0.2 p per kWh compared to a delivered domestic price of around 10 p per kWh.

In the US, there were 200 to 300 stock exchanges before the telegraph, but most of these were unnecessary and unprofitable once the telegraph made financial transactions at a distance easy and drove down transaction costs. An early experimental system (Schilling, 1832) led to a proposal to establish a telegraph between St Petersburg and Kronstadt, but it was never completed. He used the heliograph to fill in vast, thinly populated areas that were not covered by the electric telegraph. Electric current first flows out the top of the battery, through the wire and bulb and then returns via the bottom wire. To work out the number of kwh, you divide the power in watts by 1000 to convert to kilowatt (kW) and then multiply by time in hours to give kWh. To get the current in each phase, yes you add the loads to get the total wattage (in a phase) and divide by 208 for a star connected phase and 360 for a delta connected phase. Divide watts by volts to calculate amps.

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