# What is control and automation?

What is control and automation?

## Related questions

Description : Why do we use automation?

Description : State the need of automation.

Answer : Need of Automation in Process : * To fulfill the demand of product at right time. * To reduce the human errors and involvement of human being in the process. * For better productivity. * For better ... of process. * For better quality. * For reducing man power. * For reducing cost of product.

Description : Automation

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Description : What is the automatic control system?

Description : What are the advantages of open loop control system?

Answer : Open loop control system are simple to design. Open loop control system are generally stable.

Description : What are the different types of control systems?

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

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 : 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

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

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

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 : 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

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

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

Description : What is the difference between a line voltage and low voltage control system?

Description : What is HT and LT control panels?

Answer : HT Panel is like LT Panel except that it is used for high tension cables. LT Panels :LT Panel is an electrical distribution board that receives power from generator or transformer and distributes the same to various electronic devices and distribution boards.

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

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 : What is a phase control thyristor?

Description : What are the electromagnetic waves used in remote control?

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

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

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

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

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.

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 : 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

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

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

Description : Explain the principle of ON-OFF control and phase control of AC voltage controller with suitable circuit and waveforms.

Answer : The integral cycle control (on-off control) and phase angle control are the two types of AC voltage controller. The principle of ON-OFF control: The on-off control is also called an integral cycle ... control. In phase control, the switch is on for some period of each cycle.

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

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.

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 : Speed control of the motor using TRIAC

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

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

Answer : i) Function of Moderator :- Moderator is to moderate or reduce the speed of fast neutron to help the fission process.  ii) Function of sheilding : Shielding is to protect environment, ... from reactor core and transfer it in heat exchanger for producing steam at high pressure and temperature.

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

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

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.

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

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

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

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

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.

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

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

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

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

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

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

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

Answer : Series motor has the poorest speed control.

Answer : The armature voltage control of D.C. motor provides constant torque drive.

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

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.

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

Description : Explain series switching control of AC load. Single phase resistance load - Integral half cycle control Phase control - Resistance load

Description : Explain the pulse width modulation technique for control of AC output voltage.

Description : Armature control of DC motor

Answer : Armature control of DC motor

Description : Field control of DC motor

Answer : Field control of DC motor

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