Operation Manual Part 1

Digital Liquid Cooled UHF
TV Equipment
Detailed operational description
9946 V1
45321648.01 104 A E
preliminary
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Numéro / Number Doc. Rev. Lan
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16/06/2006
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Information contained is this document is confidential, is THOMSON property and cannot be disclosed in whatever form without prior written authorization of THOMSON.
However this changeover command is not confirmed if the Reserve exciter is currently on-air or one of
the following faults signals is received from the Reserve exciter:
♦ reserve exciter fault,
♦ no MPEG-2 signal at input.
Automatic transmitter on-air/off-air switch (auto start)
As soon as the fault processing system detects that there is neither an MPEG-2 signal at the input of
the on-air exciter nor at the input of the reserve exciter it automatically switches the transmitter off-air.
As soon as the fault processing system detects that there is an MPEG-2 signal at the input of the on-
air exciter or/and at the input of the reserve exciter it automatically switches the transmitter to air.
If an automatic changeover has taken place and the transmitter has not been re-initialised, the system
only takes note of whether or not there is a signal at the input of the exciter connected to the antenna.
Re-setting of synthesiser
If it is detected that the synthesiser is unlocked the "fault processing system" sends a command for its
re-setting which includes the frequency value.
Notes:
When a multiplex card fault appears, the status data, which should pass through the
card, will not be picked up by the system. When this happens some faults will not be
processed.
Although to a certain extent the various units are protected by the system the following
units have their own automatic protection systems:
♦ amplifier power supply,
♦ amplifiers,
♦ exciter system.
2.3.5.4. Protection system
There are some surveillance devices which force the transmitter to be shut down when they detect
faults. All the surveillance devices are connected together in a continuous loop system. As soon as a
fault appears, the loop protection system forces a transmitter off-air switch by switching off the
amplifier power supplies.
The protection system remains in operation when the Central Processing Unit is not in circuit. Thus the
transmitter is protected even when the control system is faulty.
The following are the elements of the loop protection system :
♦ station protection system,
♦ cabinet protection system,
♦ data on the status condition of the mains isolator in the mains distribution panel,
♦ status data on the mains input system (phase inversion and unbalanced phase conditions),
♦ surveillance device which monitors the temperature of the output liquid from the internal cabinet
cooling system,
♦ surveillance device which monitors the cooling system motor and the presence of mains on the
motor,
♦ surveillance device which monitors the liquid flow from the internal cabinet.
The protection system is switched on or off by the on/off command from the Central Processing Unit or
by the on-air/off-air overrides command from the On-Air exciter if the Central Processing Unit is not
operational.