What term is used to describe large over-voltages that develop suddenly on electric circuits?

The term that describes large over-voltages developing suddenly on electric circuits is "surges or transients." This designation reflects the nature of these voltage increases, which can occur due to various factors such as lightning strikes, sudden load changes, or switching in electrical systems. Surges or transients can pose significant risks to electrical equipment, potentially causing damage or malfunction if not properly managed.

In the context of electrical engineering and circuit protection, understanding the occurrence of surges is essential for implementing adequate protective measures, such as surge protectors or voltage suppressors, to safeguard sensitive equipment from these rapid voltage changes. The term also emphasizes the transient nature of such events, which are typically short-lived but can have immediate and impactful consequences on circuits.

Other terms like spikes and pulses might depict similar concepts but often lack the broad context and characteristics associated with surges and transients. Oscillations refer to repeated variations in voltage or current and are typically not characterized by sudden over-voltages, thus differentiating it from surges or transients.