KW control mode for Diesel Engine

In KW control mode the engine load output is the vital factor,speed is controlled for safety purpose.

That is the engine output load is maintained with a reference load.while the engine speed is maintained within safe region.

KW control mode is used in power plants.

What is Resistance thermometer or resistance temperature detectors (RTDs)

Resistance thermometer or resistance temperature detectors (RTDs) is a temperature sensor to measure temperature by the property of changing resistance of the metal used in RTD's.

The RTD is made of pure metal,whose resistance change property with temperature is linear.Different resistance and corresponding temperature data is documented to use RTD as a thermometer.

Generally platinum is used as the metal in RTD's.

What is Thermistor and difference with RTD

Thermistor is a sensor to sense temperature.It is basically a resistor whose resistance varies with temperature.

Thermistor=Thermal+resistor -the naming of thermistor.

Difference between Thermistor and RTD:

• As construction material only ceramic or polymer is used in thermistor,where RTD is made of pure metal.
• As temperature response RTD's are useful over larger temperature range and thermistor for -93 to 130c.

Principle and theory of motor operation

The discovery that led to the invention of the electric motor was simply this:
 A current carrying conductor will experience a force when placed in a magnetic field. The conductor can be any metal—iron, copper, aluminum, and so on.

The direction of the force is perpendicular to both the magnetic field and the current .

 A demonstration of this principle is easy to perform with a strong magnet, flashlight battery, and a wire and is highly recommended! Place the wire between the magnet poles and alternately connect and disconnect the wire from the battery. Each time you complete the circuit, you should feel a little tug on the wire.
The magnitude of the force on the wire can be calculated from the following equation:

 F = IBL sin θ 
where
F = force on the conductor (in Newtons)
I = current through the conductor (in amperes)
B = magnetic flux density (in gauss)
 L = length of the wire (in meters)
θ = angle between the magnetic field and current

Advantage of AC motor over DC motor

AC motors have some advantages over DC motors:
AC motors tend to be smaller, more reliable, and less expensive. However, they generally run at a fixed speed that is determined by the line frequency.

 DC motors have speed-control capability, which means that speed, torque, and even direction of rotation can be changed at any time to meet new conditions. Also, smaller DC motors commonly operate at lower voltages (for example, a 12-V disk drive motor), which makes them easier to interface with control electronics.

What is ac and dc motor

Motors are classified as either DC or AC, depending on the type of power they use.

What is an actuator

An indispensable component of the control system is the actuator. The actuator is the first system component to actually move, converting electrical energy into mechanical motion. The most common type of actuator is the electric motor.

Working principle of Air Operated Diaphragm Pumps

Air Operated Diaphragm Pumps are oscillating positive displacement pumps with two pump chambers arranged opposite each other. Both of these are separated by a diaphragm each into an air and a fluid section.

Both diaphragms are linked by a piston rod, so that with every stroke product is displaced to the outside from the one pump chamber and product is drawn into the opposite pump chamber. The four drawings opposite describe the sequence of a complete cycle consisting of a suction and pressure stroke, an empty and a filled pump chamber.

 In order to explain the function the product to be pumped was highlighted in colour.

By filling the right hand air chamber (dark grey) the right hand diaphragm is pressed towards the outside. The piston rod thereby pulls the left hand diaphragm to initial position. Valve ball (1) is pulled out of its position, product (grey) flows into the left hand pump chamber. At the same time valve ball (2) is fixed in end position by the vacuum. The left hand pump chamber is thus completely filled with product (grey).

After switching of the control valve air flows into the left hand air chamber (dark grey), the right hand air chamber is vented. The suction process (see A) now takes place in the right hand pump chamber. Product (dark grey) is drawn in , product (light grey) in the left hand pump chamber is displaced to the outside. Valve ball (1) presses down, closes and valve ball (2) opens the flow path for product to the pressure outlet port.

Air operated Diaphragm pump schematic

Air operated Diaphragm pump schematic

• 1 Discharge manifold 
• 2 Top valve ball (closed during suction)
•  3 Diaphragm 
• 4 Pump chamber
•  5 Silencer
•  6 Bottom valve ball (opened. Medium flows into chamber)
•  7 Top valve ball (open. Product is pressed out)
•  8 Air chamber (the drive air displaces the medium via the diaphragm and at the same time pulls back the second diaphragm)
•  9 Bottom valve ball (closed during delivery) 
• 10 Suction socket 
• 11 Air control unit 
• 12 Outer piston 
• 13 Inner piston

What is Diaphragm pump?

A Diaphragm pump is a positive displacement pump, that use a diaphragm,suitable non return check bulb to pump fluid.

Here Positive displacement means trapping some fluid in a chamber then pump to delivery by displacement.
Diaphragm material-rubber,taflon,thermoplastic etc

Working principle of Diaphragm pump

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What is Position Sensors

Reports the physical position of  an object from a reference point to the control system.
Position might be -

• Angle - in degree.
• Linear distance-inch,cm

What is Sensor or transducer

Sensor sense from a system and informs it to the control system.Sensor may converth the signal so that the control system can understand this.

Sensor may sense

• Electrical parameter.-Current,voltage
• Mechanical parameter-heat,light,speed,distance.

What is Zero voltage switching in SSR

The line current is switched on at the precious moment of Ac 0 voltage.This eliminates the sharp output voltage rise time and electromagnetic interference noise (EMI)

SSR-Solid state relay,in details

A SSR or solid state relay is used in place of Electromagnetic relay (EMR).

Solid State relay to drive motor

Solid State relay circuit diagram

Here SSR input out terminals are analogous to EMR coil and contact.

Input to SSR is 5,24 VDc or 120 VAc.

Input and output terminals are electrically isolatedcalled galvanic isolation thus saving the delicate motor control circuit from spike,fault current from power circuit.

SSR-Solid state relay:Advantage & disadvantage

Solid state re;lay has advantage over EMR or electromagnetic relay.
Advantage:

1. Has no moving parts thus immune to shock and vibration.
2. As an electronic device,it requires low voltage.
3. They are long lasting then EMR

Disadvantage:

1. Can be false triggered by electrical noise.
2. When on,there will be power loss due to some voltage drop.
3. Lethal leakage current when its off state.

What is ladder diagram details

Electrical Ladder diagram simplifies a circuit diagram.
There are two component in ladder diagram-

1. Power component:Motor,fused relay,Circuit breaker.
2. Control component:Input output device, that make the current flow or disrupt to power component.

Why we need electrical ladder diagram

Electrical ladder diagram simplifies an electrical schematic diagram,thus it is easy to understand what an electrical circuit diagram is showing.

Its like a global structure,understandable to technician all over the world.

What is electromechanical relays

An electromechanical relay is a device that use electromagnet to provide force to open or close a switch contact.
In other words its an electrically powered switch.

Different types of switch

 A mechanical switch is a device that can be open or close there by allowing a current or not.