04-03-2011, 10:29 AM
PP-I.ppt (Size: 2.38 MB / Downloads: 170)
DIFFERENCE BETWEEN RELAY PANEL & PLC.
Relay Panel – It is an operating on analog system.
PLC – It is an operating on digital system.
Relay Panel –The maximum time any change in input is reflected in any output is t1.
PLC – The maximum time any change in input is reflected in any output is t1+t2+…+ Tn.
Relay Panel –Since this is made from analogue components. It is possible to replace. A logic section without stopping execution of other logic sections if wired correctly.
PLC – This is made with a digital micro-controller. The micro-controller must be halted to replace a logic section. All other logic sections will stop operation.
Relay Panel –Since parallel execution of logic sections, all outputs are a function of one set of inputs.
PLC – Since serial execution of logic sections, all outputs may not be a function of one set of inputs.
Example: input I2 may change as the micro-controller is processing Logic section. Therefore Q1 and Q2 are based on different inputs.
PLC is the much less complex than large relay based system.
PLC is the very flexible due to network architecture compare to relay panel.
PLC is the virtually self-documenting compare to relay panel.
PLC is the very space efficient and less manpower required to install compare to relay panel.
PLC is the upfront material costs are similar, but savings on installation, maintenance, and troubleshooting increase rapidly as system size increases compare to relay panel.
PLC`s reliability in industry and lab experience demonstrate PLCs comparable to relay system.
PLCs huge knowledge base in industry compares to relay panel
PLCs training and operating is very easy to handle its hardware and programming is also easy to learning.
Its ability to monitor every sensor speeds debug and repair.
In the PLC have no complicated wiring compare to relay panel.