Signal Conditioning For Overcurrent Relay Application. OP-AMP

Over Current Relay( OP-AMP)

Input & Output Terminals of an OP-AMP

An op-amp has two input terminals and one output terminal. The op-amp also has

two voltage supply terminal as seen above. It has a differential input and a single

ended output. The terminal marked as negative (-) is called as an inverting

terminal, and the terminal marked as positive (+) is called as a non-inverting

terminal of the operational amplifier. If we connect an input signal at the

inverting terminal (-) of the op-amp than the amplified output signal is π radians

(180°) out of phase with respect to the applied input signal, whereas if an input is

connected to the non-inverting terminal (+) than the output signal obtained will

be in phase i.e. it will have no phase shift with respect to the input signal.

 The circuit has a precision rectification block, an amplifier, a low pass filter and a unity gain buffer.

An operational amplifier or OP-AMP is a DC-coupled voltage amplifier with a very
high voltage gain. Op-amp is basically a multistage amplifier in which a number of
amplifier stages are interconnected to each other in a very complicated manner.
Its internal circuit consists of many transistors, FETs and resistors. All this occupies
a very little space. So, it is packed in a small package and is available in the
Integrated Circuit (IC) form. The term OP-AMP is used to denote an amplifier
which can be configured to perform various operations like amplification,
subtraction, differentiation, addition, integration etc.

Power Supply for an OP-AMP
As seen from the circuit symbol above it has two input power supply terminals
+VCC and –VCC. For the operation of an op-amp a dual polarity DC supply is
essential. In the dual polarity supply the +VCC is connected to the positive supply
of one power source or battery and the –VCC terminal is connected to the
negative supply of another source. However few op-amps can also operate on a
single polarity supply. Note that there is no common ground terminal in the opamps
hence the ground has to be established externally.


Working Principle:
1. Open Loop operation
2.Closed Loop operation




Applications:
The integrated op-amp’s offers all the advantages of IC’s such as high reliability,
small size, cheap, less power consumption. They are used in variety of
applications such as Inverting & Non-inverting amplifiers, Unity gain buffer,
Summing amplifier, Differentiator, Integrator, Adder, Instrumentation amplifier,
Wien bridge oscillator, Filters etc.