What type of transformer is required as the power source for a power-limited fire alarm circuit?

The correct type of transformer required as the power source for a power-limited fire alarm circuit is a Class 2 transformer. Class 2 transformers are specifically designed to provide a limited output voltage, which helps in minimizing the risk of electric shock and fire hazards. They have strict limits on output voltage and current, ensuring safe operation within fire alarm systems, where reliable and safe performance is essential.

In residential and commercial fire alarm systems, power-limited circuits are crucial because they reduce the potential for electrical fire risks while still providing adequate power for notifications and alarms. The Class 2 rating means that the transformer can deliver a limited amount of power without posing a significant risk to safety, which is why they are the preferred choice for these applications.

Other transformers listed, such as Class 1 and Class 3 transformers, are not suitable for power-limited fire alarm circuits due to their higher output capabilities and associated risks. A standard transformer does not meet the safety standards specifically required for fire alarms, as it may not have the necessary restrictions on voltage and current to ensure safe operation. Class 2 transformers are tailored to such applications, making them the ideal choice.