Tesira Operation Manual
11. Operation and performance
D SERIES Tesira Operation Manual rev 1.0.0
29
The attack time of the VHF protection circuitry also changes with frequency, becoming shorter at higher
frequencies. This is shown in Figure 11.5.
Full output voltage
Time [ms]
1400
1200
1000
600
800
400
20
200
0
0 5
10 15 20 25 30
Frequency [kHz]
Fig 11.5: VHF Protection Attack Time Variations
The VHF protection circuit is NOT a limiter and does not alter the amplier’s frequency response. It is implemented
solely to detect continuous VHF content. HF content of normal music or speech signals at peak levels will be
passed in full. Operation of the VHF protection circuits is indicated by one (or more) of the output channels’
showing steady red. The adjacent fault message will show VHF FAULT. It is also reported as a fault via the control
network. Refer to Section 14.1 for more information on warnings and faults.
11.3.11. Short Circuit Protection
A low impedance or short circuit at the power output terminals is detected when the output current is high (Current
Peak Limiter is active) and, simultaneously, the peak output voltage is below a predetermined threshold. When this
situation occurs, the output stage is muted to protect it from damage.
Operation of the short circuit protection system is indicated by Amp channel LED showing steady red and a
corresponding text description will register in Tesira and CAFÉ software programs. Refer to Section 14.1 for more
information on warnings and faults.
The presence of a short circuit (or low impedance) is re–tested every six seconds, and the output remains muted
until the fault clears.
11.3.12. Power supply protection
The power supply is very advanced and has several internal control and monitoring functions. Should any of these
fail, the power supply will shut down to prevent damage or limit severity of the failure. If the power supply shuts
down, audio will be muted. Power supply faults, or power supply needs service faults, are indicated by a red LED
and associated error messages registered in Tesira and CAFÉ software programs.
In the extreme event of simultaneous low mains voltage supply and high power demand, the amount of incoming
energy may not be sufcient for continued operation. The power supply will then be forced to shut down. This
condition is a power protect fault, indicated with a red LED and associated error messages registered in Tesira and
CAFÉ software programs.