In a relay circuit what is used to maintain the operation of

In a relay circuit, what is used to maintain the operation of the circuit after the start button has been pushed?_________ What device is used by the overload relay to sense motor current?________ In the figure below, how is the circuit maintained after the start pushbutton is released? ________ Why should the input of a gate not be left disconnected?________ Why are the inputs to gate taken high through a resistor instead of low through a resistor? _______

Solution

1> In the Relay circuit , when the start button is pushed , current flows through the relay coil and normally overload contact to the power source is close. When current flows through Relay coil , the contacts connected in parallel with the start button close. These contacts maintain the circuit to coil when the start button is released and returns to its open position.

2> Buffer is used

3> figure is not given

4> input is not left disconnected because if gate is TTL than it will sense as logic 1 and if it is ECL than it will sense logic 0

5> resistor consumes power so there will be voltage drop and gate input need less voltage and in case of LOW , nothing is needed , we can directly connect to ground.