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    How to Explain Phone Supervision Time to AHJ for FPD-7024, D7024, and DS 94400 Series

    Issue - Can the phone supervision time be changed?

    Solution - No changes can be made the supervision time. It is either ON or OFF.

    While the communicator is idle, it monitors the primary and alternate telephone lines by “sniffing” the line for trouble. The communicator sniffs each line every 12 sec. When a trouble remains after three samples, 36 sec, it sends a Trouble Report and activates the yellow trouble LED.

    Trouble Telephone:

    To troubleshoot telephone monitor problems:

    1. Use a voltmeter to measure the voltage across each telephone line (tip to ring) while the telephone line is idle. • Generally, this standby Telco battery voltage ranges from 30 VDC to 50 VDC. Any voltage above 5 VDC is accepted by the control panel. • The polarity of the voltage does not matter.
    2. Check for other devices that might use the telephone line, such as fax machines, credit card verifiers, or PBX systems. • Note that NFPA 72 requirements mandate a dedicated telephone line for fire reporting. • If the devices cannot be removed, ensure they are wired so the control panel's line seizure relay disconnects them when needed. • Measure the line voltage while these devices are in use, ensuring it remains above 5 V.
    3. Check for intermittent faults in the telephone line. • Make a test call and verify the line is free of distortion and noise. • Temporarily swap Lines 1 and 2 on the control panel to verify the problem indication moves to the control panel's other telephone line channel. In this case, the telephone line is causing the problem rather than the line monitor.
    4. Verify the fault message is Phone Fault and not Com Fault. • Com Fault is often caused by failing to program a telephone number or account number for Phone Number 2 while routing reports to Line 1, Backup Line 2. • If only one telephone number is available for reporting, set report steering for all events to Phone 1 only. • Com Fault can also be caused if one of the telephone lines has Telco battery voltage, but does not complete a call. Make test calls to the receiver(s) on both telephone lines, listening for the receiver ACK tone.
    5. Ensure two telephone lines are available. According to NFPA requirements, the Auto Test Report is sent on a different telephone line each time it is sent. If only one telephone line is connected to the control panel, a Com Fault is generated on every other test call. The voltage present during ringing for an incoming call can be more than 100 VAC.


    Part numbers FPD-7024, D7024, DS9400, DS9400I, DS9400M

    Version history
    Last update:
    ‎05-17-2018 01:57 PM
    Updated by: