What type of relay design is characterized by a plug-type configuration?

The type of relay design characterized by a plug-type configuration is the plug type relay. This design features a modular approach where the relay can be easily inserted or removed from a socket, allowing for straightforward installation and maintenance. This configuration is advantageous in systems that require frequent adjustments or replacements, as it minimizes downtime and labor costs.

Plug type relays generally include terminals that connect to a base or socket, making them capable of being integrated into various systems without complex wiring. They also often include mechanisms like latching or switching to perform their intended function based on electrical signals.

In contrast, choices like shunt trip circuit breakers and electrical interlocks refer to specific safety devices used in circuit protection and control rather than to relay configurations. Full wave rectifiers deal with converting alternating current (AC) to direct current (DC), which is not related to relay design. Thus, the plug type relay stands out as the correct answer based on its unique and practical design.