The emergency stop switches have what type of contacts?

The emergency stop switches are designed to interrupt power to critical components in a system, such as the fuel transfer pump. These switches generally have closed contacts during normal operation, allowing the electrical circuit to function continuously. When activated, the emergency stop switch opens the circuit, cutting power to the pump and ensuring safety by quickly shutting down operations.

The correct answer indicates that the contacts are closed under normal conditions, which allows for the continuous operation of the pump's control circuitry. This design ensures that the emergency stop can effectively halt operations by breaking the closed circuit when needed, providing a vital safety mechanism to prevent hazards during operation.

In contrast, the other options incorrectly suggest that the contacts could be open or involve high voltage scenarios, which do not align with the standard operational requirements for emergency stop switches. These options fail to recognize the function of ensuring that the system is operational until an emergency requires an immediate shutdown, highlighting the importance of having closed contacts in a safe and efficient fuel transfer pump control system.