PE CONVERTERS.pptx

PE CONVERTERS

-By G.AMIT KUMAR M.TECH MANUFACTURING ENGG 140926015

CONTENTS

.• INTRODUCTION

.• PRESSURE SWITCH

• TYPES OF PRESSURE SWITCH

.• WORKING PRINCIPLE

.• APPLICATION

.• REFERENCE

INTRODUCTION

Electro Pneumatic control integrates pneumatic and electrical technologies, is more widely used for large applications.

In Electro Pneumatics, the signal medium is the electrical signal either AC or DC source is used.

Working medium is compressed air and operating voltages from around 12 V to 220 Volts

The resetting of the valve is either by spring [single Solenoid] or using another solenoid [Double solenoid Valve].

Control of Electro Pneumatic system is carried out either using combination of Relays and Contactors or with the help of Programmable Logic Controllers [PLC].

PRESSURE SWITCHA pressure switch is a form of switch that closes an electrical contact when a certain set pressure has been reached on its input.

Another type of pressure switch detects mechanical force; for example, a pressure-sensitive mat is used to automatically open doors on commercial buildings.

The switch may be designed to make contact either on pressure rise or on pressure fall.

The pressure switch may be adjustable, by moving the contacts or adjusting tension in a counterbalance spring.

Industrial pressure switches may have a calibrated scale and pointer to show the set point of the switch.

A pressure switch will have a differential range around its setpoint in which small changes of pressure do not change the state of the contacts. Some types allow adjustment of the differential.

The contacts of the pressure switch may be rated a few tenths of an ampere to around 15 amperes, with smaller ratings found on more sensitive switches.

Often a pressure switch will operate a relay or other control device, but some types can directly control small electric motors or other loads.

An electronic pressure switch incorporates some variety of pressure transducer (strain gauge, capacitive element, or other) and an internal circuit to compare the measured pressure to a set point.

Such devices may provide improved repeatability, accuracy and precision over a mechanical switch.

Electronic pressure switch with LED display

Solid-State Pressure SwitchesSolid-state pressure switches contains following characteristics:

1. One to four or more switch points, 2. Digital displays, 3. Analog and digital outputs, 4. Full programmability. 5. Provide a proportional 4-20 mA analog signal or digital output.

OTHER TYPES1. High Pressure Switch2. Diaphragm Pressure Switch3. Low Pressure Switch 4. Liquid Level Pressure Switch5. Air Pressure Switch 6. Air Compressor Pressure switch

1. High pressure switch:- This pressure switch is designed for the demanding requirements of lager, heavy duty commercial air compressors (up to 400 psi). Resists the harsh conditionsMade up of stainless steel

2. Diaphragm Pressure Switch:- The diaphragm pressure switch is available for various sumps, effluent, and sewage application to control the liquid level. -For to turn-on or turn-off the pump

3. Low Pressure Switch:- Widely used in food waste disposer, pumps for swimming pools, hot tubs, sanitary equipment, medical equipment etc. -The low pressure switch has Operating Pressure Range 20 mbar to 1000 mbar.

4. Liquid Level Pressure Switch:-The liquid level pressure switch can be used to control the level of water or other non-hazardous liquids. -Basic functioning operation is similar to diaphragm pressure switch. -Operable within the range of -10~85º C.

TRANSDUCER

A transducer is a device that converts a signal in one form of energy to another form of energy.

Energy types include (but are not limited to) electrical, mechanical, electromagnetic(including light), chemical, acoustic and thermal energy.

Transducer commonly implies the use of a sensor/detector, any device which converts energy can be considered a transducer.

Transducers are widely used in measuring instruments.

PRESSURE TRANSDUCER

A pressure transducer, sometimes called a pressure transmitter, is a transducer that converts pressure into an analog electrical signal.

Although there are various types of pressure transducers, one of the most common is the strain-gage base transducer.

The conversion of pressure into an electrical signal is achieved by the physical deformation of strain gages.

The strain gauges are bonded into the diaphragm of the pressure transducer and wired into a wheatstone bridge configuration.

Pressure applied to the pressure transducer produces a deflection of the diaphragm which introduces strain to the gages.

The strain will produce an electrical resistance change proportional to the pressure

Cont….

PRESURE TRANSDUCER TYPES1. PC Board Mountable Pressure Transducers:- -PC board mountable pressure transducers are generally compact economical pressure transducers designed to mount on an electrical PC board and be integrated into other products.

2.General Purpose Transducers-General purpose pressure transducers are the most common since they are designed to fit the broadest set of applications.

3. Heavy Duty/Industrial Pressure Transducers-Heavy Duty/Industrial Pressure transducers feature a much more rugged enclosure than other transducers. -They are designed to accommodate heavy industrial environments. -They also often feature a scalable 4-20mA output that provides much greater immunity to electrical noise which is not uncommon in industrial environments.

4. High Stability/High Accuracy Pressure Transducers-Most pressure transducers feature an accuracy of 0.25% of full scale or higher. -High stability and high accuracy pressure transducers can offer errors as low as 0.05% of full scale, depending on model.-Although more expensive than general purpose transducers, they may be the only option if high precision is required.

WORKING

A pressure switch is a pneumatic-electric signal converter.

Pressure switches are used to sense a change in pressure, and opens or closes an electrical switch when a predetermined pressure is reached.

Bellow or diaphragm is used to sense the change of pressure. Bellows or Diaphragm is used to expand or contract in response to increase or decrease of pressure.

The above figure shows a diaphragm type of pressure switch.

When the pressure is applied at the inlet and when the pre-set pressure is reached, the diaphragm expands and pushes the spring loaded plunger to make/break contact.

Uses of pneumatic pressure switches include:-

-Switch a household well water pump automatically when water is drawn from the pressure tank.

-Switching off an electrically driven gas compressor when a set pressure is achieved in the reservoir.

-Switching off a gas compressor, whenever there is no feed in the suction stage.in-cell charge control in a battery.

-Switching on/off an alarm light in the cockpit of an aircraft if cabin pressure (based on altitude) is critically low.

-Air filled hoses that activate switches when vehicles drive over them. Common for counting traffic and at gas stations.

APPLICATIONPressure switches in their simple form detect a pressure change, and at a predetermined level or set point, open or close a contact.

1. Safety devices2. Alarms3. Control elements

within a system4. Steam power plant5. Electric motors6. Gas compressor7. Automobiles

8. Pumps9. Boilers10.Steam turbines