1 Answer

Answer :

In Ward-Leonard control the lower limit of speed is imposed by residual magnetism of the generator.

Related questions

Last Answer : The main disadvantage of the Ward-Leonard control method is high initial cost, high maintenance cost, low efficiency at light loads.

Last Answer : Ward-Leonard control is basically a voltage control method.

Last Answer : Speed control by Ward Leonard method gives uniform speed variation in both directions.

Last Answer : For constant torque drive armature voltage control speed control method is preferred.

Description : Speed control of the motor using TRIAC

Last Answer : Speed control of the motor using TRIAC:  This basic phase triggering circuit uses the triac in series with the motor across an AC sinusoidal supply. The variable resistor, VR1 is used ... meaning that it may not trigger at the exact same point for each positive and negative half cycle.

Description : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque  (1) Decreases (2) Increases (3) Remains constant (4) None of the above

Last Answer : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases 

Last Answer : Series motor has the poorest speed control.

Last Answer : Usually wide and sensitive speed control is desired in case of colliery winders.

Last Answer : Speed control of a universal motor is achieved by varying field flux with tapped field windings, connecting rheostat in series, applying variable voltage by means of silicon controlled rectifier, applying variable voltage by means of variable auto-transformer.

Last Answer : The speed control of universal motor used for sewing machines is by varying the resistance.

Description : What are the speed control methods of dc motor?

Last Answer : Field control of DC motor Armature control of DC motor

Description : speed control methods of three phase induction motor?

Last Answer : Speed control of three phase induction motor

Description : The chief advantage of Ward-Leonard system D.C. motor speed control is that is  1. Can be used even for small motors 2. has high overall efficiency at all speeds 3. Gives smooth, sensitive and wide speed control 4. Uses a flywheel to reduce fluctuations in power demand

Last Answer : The chief advantage of Ward-Leonard system D.C. motor speed control is that is Gives smooth, sensitive and wide speed control 

Description : Why does the speed of a DC shunt motor decrease as the load increases?

Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

Description : Under constant load conditions, the speed of a d.c. motor is affected by?

Last Answer : Under constant load conditions, the speed of a d.c. motor is affected by field flux.

Last Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.

Description : The method of D.C. motor speed control shown in the illustration is known as _____________. EL-0101 A. Ward-Leonard B. Sperry-Rand C. Atlas-Copco D. Burmeister-Wain

Last Answer : Answer: A

Description : The basic type of D.C. motor speed control where a generator armature directly feeds the motor armature and the motor and generator fields are excited by a separate D.C. source is called ___________________. A. Burmeister-Wain B. Ward-Leonard C. Sperry-Rand D. Atlas-Copco

Last Answer : Answer: B

Description : is an open loop control system. (a) Ward Leonard control (b) Field controlled D.C. motor (c) Stroboscope (d) Metadyne

Last Answer : Ans: B

Description : If the math was easier then could we have a speed limit on automobile acceleration?

Last Answer : Our test cars had numerous g sensors to measure acceleration. It was fun. It was also possible to calculate it on the fly. You can do it yourself with a cheap, used, mechanical, air craft angle of attack meter. You can get them for $5–10 at army surplus stores. 45 degrees means 1 g.

Description : Should fast acceleration be included in the speed limit?

Last Answer : How?

Description : Why don't people take control of their news feeds on Facebook?

Last Answer : Because some people are drama mongers, even though they claim that they hate drama. Other people want to be in the know even though they can't stand to see what some people have to say ... know how to change their settings. Some people would prefer if everybody agreed 100% with what they believe.

Description : Explain In Brief The Control And Timing Circuitry Of The 8085.?

Last Answer : Answer :The timing and control circuitry section of the 8085 is responsible for the generation of timing and control signals so that instructions can be executed. The types of signals involved ... of control signals for the executions of instructions and for the sync between external devices.

Description : MCQ on Motor Control Center

Last Answer : 1. MCC stands for ______ a. Motor Control Center b. Motor Control Cost c. Machine Components Center d. None of the above Answer : a. Motor Control Center 2. MCC contains _____ a. Fuse b. MCB c. ... a) Start the motor b) Accelerate the motor c) Decelerate the motor d) Stop the motor Answer : a

Description : How To Control Obesity

Last Answer : How To Control Obesity According to statistics, one in every three American adults is classified obese. Obesity is becoming a large problem in developed countries today. It increases the risk of serious ... any problem with controlling your obesity. In the end, you will benefit greatly from it.

Description : How To Control Blood Sugar

Last Answer : How To Control Blood Sugar Any person suffering from diabetes knows that maintaining blood sugar level is important to avoid complications. Blood sugar refers to the amount of glucose present in a person's blood. ... but the trade-off is more than worth the trouble. After all, the cost is your life.

Description : How to Choose a Birth Control Method

Last Answer : How to Choose a Birth Control Method Birth control methods depend on the couple's needs and commitment to the method. Some couples just need to prevent pregnancy while others wish to avoid sexually- ... unplanned sex, a broken condom or failure to take birth control pills two days in a row.

Description : How to Control Weeds in Your Garden

Last Answer : How to Control Weeds in Your Garden Weeds are unwanted plants which grow in your garden, crops, lawn or other agricultural areas, along with the other wanted and valuable plants. They are ... which have grown into your beautiful garden and have become an obstacle in their growth and development.

Description : Bacteria Control Tips

Last Answer : Bacteria Control Tips Although most micro organism in the outside world are harmless. It is necessary to realise that some pathogenic species are often mixed with non-pathogenic ones and special ... For being healthy, I hope, tips mentioned above for bacteria control definitely useful to you.

Description : Draw the labeled block diagram of process control system and explain each block.

Last Answer : Explanation - Process control system consists of process or plant, sensor, error detector, automatic Controller, actuator or control element. 1) Process or plant- process means some manufacturing sequence ... process which changes the process variable. Output of this block is denoted by u .

Description : State the purpose of lighting control. List the different types of dimmer.

Last Answer : Purpose of Lighting Control:- 1. To turn ON or OFF the lamps 2. For dimming: The dimming control permits the adjustment of lighting over a range. 3. For changing the lighting levels ... operated dimmer 6) Triac operated Dimmer 7) PWM (Pulse width modulation) Controlled technique.

Description : Illustrate with neat wiring diagram a single lamp control by two point method.

Last Answer : Single lamp control by two point method:  This system is commonly used for stair case wiring. It consists of two way switches (the switch operates always in one of the two possible positions) the ... the person will change the position of switch S2, so that the lamp will be switched OFF'.

Description : Define the following terms : (i) Base Station (ii) Control Channel (iii) Mobile Station (iv) Page 

Last Answer : i) Base Station: - A fixed station in a mobile radio system used for radio communication with mobile stations. Base stations are located at the center or on the edge of a coverage region ... the page throughout the service area using base stations which broadcast the page on a radio carrier.

Description : What are the disadvantages of Open loop control system?

Last Answer : Open loop control system are less reliable. In open loop control system Optimization is not possible. Open loop control system are less accurate.

Description : Draw and explain bulk correction method for power factor & control.

Last Answer : Bulk correction method for power factor & control: i) Here individual starter controls the capacitors located at distribution panel. ii) Centralized compensation is employed in large industrial plants where many ... capacitor units in steps to maintain P.F. more than preset limit (0.95). 

Description : State the function of following components of a nuclear power station: i) Moderator ii) Shielding iii) Control rod iv) Coolant 

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Description : Write function of control rods in nuclear power plant.

Last Answer : Function of control rods in nuclear power plant: The function of control rod is to control the chain reaction in reactor core by adjusting its height.

Description : Write one advantage and one disadvantage each for spring control method and gravity control method.

Last Answer : Advantages of Spring Control Method: 1) The spring-controlled meters may be used in any position. 2) In some instruments, springs can be used as current leads. 3) As springs are light in weight ... only. 2) Scale is non-uniform. 3) Control weights add to the weight of instrument.

Description : State the function of former and control spring in PMMC instrument.

Last Answer : Function of Former: To support the coil and provide eddy current damping.  Function of Control Spring: To provide control torque or force and in some instruments springs can be used as current leads.

Description : Describe spring control method of producing controlling torque in measuring instrument. Write any two properties required for spring material.

Last Answer : A)Spring control method: As shown in the figure, the inner ends of the both springs are attahced to the spindle, while outer end of upper spring is attached to the lever and outer ... of spring material: 1.Non Magnetic material 2.Low specific resistance 3.Low temperature coefficient of resistance

Description : Explain spring control method with neat diagram.

Last Answer : Spring Control Method: As shown in the figure the inner ends of the both springs are attahced to the spindle ,while outer end of upper spring is attached to the lever and outer end of ... the springs are twisted in opposite direction to the motion of pointer and produce controlling torque.

Description : Quality control is aimed at: a. Maintaining the desired quality b. Exceeding the desired quality c. Continuously improving the quality d. Following the quality

Last Answer : Quality control is aimed at: a. Maintaining the desired quality b. Exceeding the desired quality c. Continuously improving the quality d. Following the quality

Description : A control system having unit damping factor will give  (1) Oscillatory response (2) Undamped response (3) Critically damped response (4) No response

Last Answer : 1

Description : A differentiator is not usually used in control system, because it : - (A) reduces damping  (B) increases error  (C) reduces gain margin  (D) increases input noise

Last Answer : A differentiator is not usually used in control system, because it : - increases input noise

Description : The meter which does not have any component in it to provide control torque is (A) Electrodynamometer for current measurement (B) Electrodynamometer for voltage measurement (C) Electrodynamometer for power measurement. (D) Electrodynamometer for power factor measurement.

Last Answer : The meter which does not have any component in it to provide control torque is Electrodynamometer for power factor measurement.

Description : A unity negative feedback control system is found to have a gain margin of 20 dB. The Nyquist plot of the system (A) crosses the real axis at +0.1 (B) crosses the real axis at -0.1. (C) crosses the imaginary axis at -0.1 (D) crosses the imaginary axis at +0.1

Last Answer : A unity negative feedback control system is found to have a gain margin of 20 dB. The Nyquist plot of the system crosses the real axis at -0.1.

Description : Precise control of reactive current flow entering the transmission and distribution systems can be minimized by using (A) synchronous condenser (B) static VAR capacitor (C) capacitor bank (D) thyristor switched reactor in parallel with capacitor

Last Answer : Precise control of reactive current flow entering the transmission and distribution systems can be minimized by using (A) synchronous condenser (B) static VAR capacitor (C) capacitor bank (D) thyristor switched reactor in parallel with capacitor

Description : Regulating-transformers are used in power systems for control of

Last Answer : Regulating-transformers are used in power systems for control of power flow

Description : Negative feedback in a closed-loop control system DOES NOT (A) reduce the overall gain (B) reduce bandwidth (C) improve disturbance rejection (D) reduce sensitivity to parameter variation

Last Answer : Negative feedback in a closed-loop control system DOES NOT reduce bandwidth

Description : The standard for long distance analog signal transmission in process control industry is (A) 4-20 mV (B) 0-20 mA (C) 4-20 mA (D) 0-5 V

Last Answer : The standard for long distance analog signal transmission in process control industry is 4-20 mA