Biamp Vocia VA-2060 Manual De Operación página 15

Output Fault Detection
The Amplifier monitors (supervises) for faults on speaker connections using a combination multiple out-of-
band (inaudible) high frequency tones for end-of-line detection, and DC current for ground fault detection.
For end-of-line detection, one or more (up to 15 maximum) ELD-1 units must be connected to the end/s
of the speaker line. End-of-line and ground fault detection may be individually enabled/disabled in the
Vocia software. To ensure correct operation of fault detection it is necessary to follow these guidelines:
•
When an ELD-1 is being used in a Vocia system it is important that the Amplifier Output Setting in
the software matches the Hardware Output setting selected on the physical amplifier (8Ω, 4Ω, 25V,
70V or 100V). See the Software Help file for more information.
•
Recorded audio messages or audio content with continuous or swept tonal components (e.g. alert
tones) and any content with significant high frequency harmonic content should be band limited
(>24dB/octave) at 15 kHz during recording. Note that program content that is distorted due to poor
recording techniques may contain excessive high frequency harmonics.
•
Signal level adjustments within a Vocia system should be set so as to minimize clipping. Severely
clipped signals may also affect the out-of-band fault detection tones.
•
The use of speaker cables that inherently attenuate high frequencies is not supported (e.g. screened
cables). Speaker cables must maintain frequency response to the end of line of less than -3dB @
20kHz at with respect to 1kHz.
•
Speaker cables longer than 500 feet may prevent correct operation of ELD-1 and Ground Fault
monitoring capabilities. An advantage of Vocia is that amplifiers may be easily distributed close to
speakers, thereby minimizing long runs of expensive and potentially lossy speaker cable.
•
Highly capacitive speaker lines or loads may prevent correct operation of the ELD detection system.
•
Legacy monitored speaker circuits that use capacitors and resistors or similar methods must have all
legacy monitoring circuitry removed for correct operation of the ELD detection system.
The amplifiers use DC current to detect whether there is an erroneous ground connection placed on
either or both speaker wires. The detection circuit will declare a fault for a resistance to ground of 50kΩ or
less. To prevent false ground fault readings, the DC resistance to ground of speaker circuits must be
100kΩ or higher (either speaker wire to ground).
•
For EN54-16 compliance, one or more ELD units must be fitted. End of Line detection and Ground
Fault Detection must be enabled in the Vocia software.
Failover Modes
Device-to-Device or Channel-to-Channel failover modes are supported. Only one type of failover mode
can be implemented per device.
Device-to-Device Failover
Amplifier units provide for Device-to-Device failover when a fault is detected. A Failover Link Cable must
be connected between the primary and the redundant units as shown. Connect ground to ground, and Pin
1 of the primary device to Pin 2 of the redundant device; connect Pin 2 of the primary device to Pin 1 of
the redundant device.
VA-4030(e) and 2060(e) Fault Detection