1. A) B)

C. A pump has a displacement volume of 100 cm3. It delivers 0.0015 m3/s at 1000 rpm and 70 bars. The prime mover input torque is 120 Nm.

a) What is the overall efficiency of the pump? b) What is the theoretical torque required to operate the pump?

Sol. a) From QT = V × n,

Given V = 100 cm3/rev

= 0.0001 m3/rev

QT = V × n

= 0.0001 m3/rev × (1000/60 revs-1)

= 0.00167 m3/s

Solve volumetric efficiency ηvol = QA/QT

= 0.0015/0.00167

= 0.898

= 89.8%

Solve mechanical efficiency ηm = PQT/TAN

= (70 × 105)(0.00167)/(120)(1000 × (2π/60))

= 0.93 = 93%

Therefore, ηtot = 0.93 × 0.898

= 0.835

= 83.5%

b) ηm = TT/TA TT = ηm × TA = 0.93 × 120 = 111.6 Nm

2 a) State the working principle of a radial piston pump with a neat sketch.

A radial piston pump is a form of hydraulic pump. The working pistons extend in a radial direction symmetrically around the drive shaft, in contrast to the axial piston pump.

These are made up of valve-controlled pump cylinders arranged in radial star-shape. They supply pressurized oil reliably up to 700 bar.

They can produce a very smooth flow under extreme pressure. Generally they are variable-displacement pumps.

In variable models, flow rate changes when the shaft holding the rotating pistons is moved with relation to the casing (in different models either the shaft or the casing moves). Output can also be varied by changing the rotation speed.

An odd number of pistons is always used to smooth the hydraulic balance. These pumps revolve at speeds up to about 1200 RPM.

B)

3 a)

3 b)

4. a) C is the answer

b) CIRCUIT DIAGRAM

5. a) discuss the I/O interfacing of PLC

PLC interface - Inputs

Digital inputs – two conditions

ON/OFF ,YES/NO, Logical "0" or "1“

Connecting –Pushbuttons

Switches

Photo sensors

Proximity switches

Digital inputs can be PNP and NPN In Unitronics controllers DI can be set to PNP or NPN –via jumpers, wiring and software

PLC interface – Outputs

Digital outputs –to switch ON/OFF devices –motors, valves, contactors, signal and lighting lamps…

Transistor outputs - output 0.5A/24V DC –fast and "long life"

Relay outputs –dry contacts –slower and shortest life.

Analog outputs –output standard 0-10V or 4-20 mA signal 12 bits

To change speed of motors, drive proportional valves, set position…

b) Merits of PLC

c)

6) a) OR ladder diagram

AND ladder diagram

NAND ladder diagram

NOT ladder diagram

b)

PLC CIRCUIT I DON’T KNOW SIR

7)

a)

o

9) a)

b)

I DON’T KNOW ANSWER SIR

C)