Spectrex 20/20SH - Hydrogen Flame Detector - Manual (Page 22)

Spectrex Inc. - SharpEye TM Hydrogen (SH) Flame Detector Manual – TM 784600, Rev. A, May 2005
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4.4 Built In Test
A. General
The detectors’ Built In Test (BIT) checks the following:
• Electronics circuitry
• Sensors
• Window cleanliness
The detector can be set to perform the BIT automatically and manually or
manually only.
B. Principles
If the result of a BIT is the same as the current status of the detector (NORMAL or
BIT FAULT), the detector's status is unchanged. If the result of a BIT differs from
the current status of the detector, the detectors’ status is changed (From NORMAL
to BIT FAULT or from BIT FAULT to NORMAL).
Note: In BIT FAULT status the detector can continue to detect a fire.
C. Manual BIT only
The BIT is initiated manually by momentarily connecting Terminal No. 3 with
Terminal No. 2. A successful manual BIT activates the following:
• FAULT relay is closed.
• ALARM relay is activated for 3 sec. (only when Function Alarm BIT at YES)
• ACCESSORY relay is activated for 3 sec. (only when Function Accessory
BIT at YES)
• 4-20mA OUTPUT current will be 15mA only when Function Alarm BIT at
YES or 10mA when Function Accessory BIT at YES and Function Alarm
BIT at NO.
Unsuccessful BIT activates the following:
• FAULT relay is released.
• 4-20mA output indicates BIT FAULT condition (2mA).
• POWER LED (yellow) flashes (4 Hz).
Note
During a Manual BIT, if Function Alarm BIT or Function Accessory BIT are in
YES position, the Alarm, Accessory Relays and 4-20mA will be activated.
Therefore, automatic extinguishing systems or any external devices that should
not be activated during BIT should be disconnected.