Voltage Scale Span of instrument = Vmax − Vmin
Vmax = 5 V
Vmin = −5V
Span = 5 −(−5) = 10 V
The melting point of Eureka is 1221 to 1300 °C
The melting point of Kanthal is 1,425 °C
The melting point of Nichrome is 1400 °C
The melting point of Graphite is 3,600°C
Hence Eureka has the least range of temperature.
Neon-lamp holders A lot of industrial electronic equipment uses neon lamps to indicate when they have been energized from the mains. If the lamp fails to glow, it means something is wrong with the supply circuit, the equipment, or the indicator itself. The neon lamps used are quite small and housed in holders 5 mm to 10 mm in diameter.
A phase sequence is an order or sequence in which the currents or voltages of different phases attain their maximum values. In a three-phase system, there are only two possible phase sequences: R-Y-B (positive Phase Sequence) and R-B-Y (Negative Phase Sequence).
The efficiency and power factor of single-phase motors are usually low. Thus at full-load a 186 W motor (1/4 hp) has efficiency and poor factor of about 60 percent. For the same size, the single-phase induction motors develop about 50% of the output as that of three-phase induction motors. The starting torque is also low for asynchronous motors / single phase induction motor.
The low power factor is mainly due to the large magnetizing current, which ranges, between 70 percent and 90 percent of full-load current. Consequently, even at no-load these motors have a substantial temperature rise. The power factor of 3-phase motors is of the order of 0.85 lagging, whereas it is 0.55 to 0.6 for single-phase motors.
The relatively low efficiency and power factor of single-phase induction motors is a consequence of their fractional horsepower ratings. The efficiency of 3-phase motors is quite high of the order of 80 to 90 %, while single-phase motors hardly work with an efficiency of 55 to 60 %.