FACP Power Supply & Battery Systems 2 — Questions and Answers
Question 1: For a non-sprinklered building, what is the minimum secondary (standby) power duration required by NFPA 72?
- 12 hours
- 24 hours
- 60 hours (Correct answer)
- 48 hours
Correct answer: 60 hours
NFPA 72 requires 60 hours of standby power for non-sprinklered buildings, significantly more than the 24 hours required for sprinklered buildings.
Question 2: What happens to an FACP when AC primary power is lost?
- The panel shuts down immediately
- The panel automatically switches to secondary battery power and generates a trouble signal (Correct answer)
- The panel activates all notification appliances
- The panel enters a diagnostic test mode
Correct answer: The panel automatically switches to secondary battery power and generates a trouble signal
When AC power is lost, the FACP automatically transfers to battery backup and initiates a trouble signal to notify the responsible party of the power loss condition.
Question 3: What is 'float charging' in the context of FACP battery systems?
- Charging batteries to 100% then disconnecting the charger
- A continuous low-level charge that maintains fully charged batteries while compensating for self-discharge (Correct answer)
- Rapidly charging a depleted battery to full capacity
- Periodically testing battery capacity at set intervals
Correct answer: A continuous low-level charge that maintains fully charged batteries while compensating for self-discharge
Float charging is a continuous low-current method that keeps batteries fully charged by compensating for natural self-discharge without overcharging them.
Question 4: When calculating battery size for an FACP, how is the alarm load component determined?
- Standby current multiplied by standby hours
- Alarm current multiplied by alarm duration converted to hours (Correct answer)
- Peak current multiplied by 24 hours
- Total ampere-hours multiplied by 0.80
Correct answer: Alarm current multiplied by alarm duration converted to hours
The alarm load component is calculated as alarm current multiplied by the required alarm duration in hours (e.g., 5 minutes = 5/60 hours), then added to the standby load.
Question 5: Which condition requires FACP battery replacement per NFPA 72?
- Battery terminal voltage drops below 14.4 V during normal standby
- Battery capacity falls below 80% of its rated ampere-hour value (Correct answer)
- Battery temperature exceeds 77°F (25°C) during operation
- Battery has been installed for more than 3 years
Correct answer: Battery capacity falls below 80% of its rated ampere-hour value
Per NFPA 72, batteries must be replaced when capacity testing reveals they can no longer deliver 80% of their rated ampere-hour capacity, regardless of age.
Question 6: What is the purpose of a battery supervision circuit in an FACP?
- To display the battery charge percentage on the annunciator
- To detect an open circuit or disconnection of the battery and generate a trouble signal (Correct answer)
- To automatically limit the charge current to safe levels
- To perform automatic periodic capacity tests
Correct answer: To detect an open circuit or disconnection of the battery and generate a trouble signal
Battery supervision continuously monitors the battery connection and generates a trouble signal if the battery becomes disconnected or an open circuit develops.
Question 7: What is the typical regulated DC output voltage of an FACP power supply used to power field devices?
- 12 VDC
- 24 VDC (Correct answer)
- 48 VDC
- 120 VDC
Correct answer: 24 VDC
Most commercial FACPs use a 24 VDC regulated power supply to power initiating device circuits, notification appliance circuits, and other field equipment.
FACP Power Supply & Battery Systems 2
For a non-sprinklered building, what is the minimum secondary (standby) power duration required by NFPA 72?