Chapter 2 Design and Function
5300.9677.72 - 2.25 - EN-4
2.1.5 Power Supply Fault (R&S VU813)
The instrument has three power supply units. The instrument controller is supplied with
power from an auxiliary power supply unit with current-limited output. All lines carrying AC
supply voltage and high current are covered to prevent touching (double insulation,
sheathed conductor+shrink-on sleeve).
If primary side components fail, the primary fuse trips. Transfer of primary side overcurrent
to the secondary side is prevented by the potential isolation of the power supplies. The sup-
ply of power to the instrument controller is safeguarded by means of the output-current lim-
itation of the auxiliary power supply unit.
In view of the power required from the current supply, the current available at the auxiliary
power supply output can be as high as 10 A and as high as 70 A at the output from the am-
plifier power supplies.
2.1.6 Damage on RF Output Side
Fault Protection mechanism Function
Damage between AC supply
input and power supply unit
Protected by primary fuse Primary fuse trips.
Damage to power supply
unit
Protected by primary fuse Primary fuse trips.
Damage between amplifier
power supplies and amplifier
board
Current limited by amplifier power sup-
plies
Current limited
Overload caused by instru-
ment controller
Current limited by auxiliary power sup-
ply unit
Current limited
Fault Protection mechanism Function
VSWR > 1.5 Measurement of forward/reflected
power at transmitter output, calculation
of VSWR in control unit, reduction of
nominal value not sufficient.
Transmitter shutdown
after sampling 3 times
Short-circuit at antenna Measurement of forward/reflected
power at transmitter output, calculation
of VSWR in control unit
Transmitter shutdown
after sampling 3 times
Open circuit at antenna Measurement of forward/reflected
power at transmitter output, calculation
of VSWR in control unit
Transmitter shutdown
after sampling 3 times
Antenna detachment Measurement of forward/reflected
power at transmitter output, calculation
of VSWR in control unit
Transmitter shutdown
after sampling 3 times
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