Final answer:
The location of protective devices like PMRs is known as substations, which play a crucial role in power distribution and protection of the electrical system.
Step-by-step explanation:
The location of protective devices such as PMR (Protective Molded Case Relay) is known as substations. These devices are components of the electrical distribution system and they protect equipment from overcurrent events by interrupting the electrical circuit if the current exceeds a certain threshold. Substations are key facilities in the power distribution network where the voltage levels are changed and where the protection and control equipment, like PMRs, are located to ensure the safe and reliable operation of the electrical system.