How to measure Flow?

Flow Strainers, Impellers, Magnetic sensing pickups. 

Turbine Meter

• good for telemetry
• errors may be caused 'coz of excessive frictional torque.

Electromagnetic flowmeter

• suitable for slurry, sludges etc
• Adv: size adaptability,No pressure drop
• Disad: for heavy slurry, high operating cost.

Hot Wire Anemometers

• more flow > more cooling
• voltage variation
• measured by POT

Using Thermister

• can measure velocity of air

Ultrasonic flow meter

• used mainly for liquid
• useful for bidec tional flow
• Adv:linear relationship
• Adv:insensitive to variation in viscocity, density and temp
• Disadv: complexity
• Disadv: relative high cost

Per Unit Impedance

Some EE Questions

Q) For eleiminating 5th harmonics in a three phase AC system, the winding pitch should be?

Choices:   2/3, 4/5, 5/6, 6/5

Q) Magnetic circuit is saturated, delivering full load current at rated volt and current. n= constant, brushes at interpolar axis. When load is switched off, terminal voltage would?

Choices:  remain same , increase, decrease, will become 0.

Q) Under which of the following conditions dc motor with compensating winding is used?

Choices:
A) Wide range of speed control above normal
B) Wide range of steady load variation with no speed control
C) Wide range of rapid variation in load

Q) What happens when field of DC shunt motor gets opened?

Q) Match?

Interpoles.................Commutation in D C machine.

Three pt. starter.........DC shunt motor

Dummy Coils............Wave Winding

Equaliser Ring...........Lap Winding

Q) The phase sequence of alternator will reverse when

a) If ( field current) is reversed, keeping direction of rotation same.
b) If remains same, direction of rotation is reversed.
c)If reversed, number of poles is doubled.
d) Number of poles doubled, If same.