Let's say that there is a simple circuit with the following components (ignore values):
- LEFT: a simple power supply (assume DC)
- TOP: load (resistor) and inductor
- RIGHT: switch
- BOTTOM: load (resistor)
I have come across numerous sources that indicate that if the SWITCH suddenly moves from a CLOSED position to an OPEN position, the circuit and its components can potentially be compromised if unprotected:
- When the switch opens, the current across the entire circuit will drop to zero really quickly (assume instantaneously), resulting in a back EMF
- The resulting back EMF voltage according to the inductance formula will be very high as the change in time will be very small
- The high voltage produced by this back EMF has the potential to damage the circuit and its components
Below are some assumptions that I hold, please advise if any of them are incorrect or incomplete:
- When the switch is closed and has reached steady state, a current will be passing through the circuit in accordance with Ohm's law (V = IR) or somewhere near there.
- When the switch is closed and has reached steady state, the current passing through every wire on the main circuit is uniform (i.e. the wire before and after the power supply has the same current passing through it).
- Current is the main factor that controls whether the wire in the circuit is damaged or not.
- When the switch is opened, the resistance across the open circuit remains the same as it was when the switch was closed, therefore the current generated by the back EMF through the circuit inversely proportional to the voltage generated by the back EMF (Ohm's Law).
- Since the current passing through the open circuit is equal to or lower than the current passing through the closed circuit (inductance over short period of time), the wires and its components should be able to withstand the back EMF without any damage (exception are voltage sensitive components such as transistors, diodes, etc).
What scenarios would result in the back EMF potentially damaging the circuit and/or its components and what solutions could be taken to mitigate the problem?