ifi T251-500A, Инструкция по эксплуатации и техническому обслуживанию

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Rev. A 10/01/08 13
4.6 PROTECTION CIRCUITS
The TWT Amplifier is designed with a variety of protection circuits to provide safeguards for the
amplifier should any adverse electrical conditions occur or if the amplifier accidentally experiences
operator deviation of the design application. Listed below are the safeguards.
4.6.1 Overheat Protection
The TWT, a critical component of this Amplifier, is mounted to a heat sink, which is in turn, air
cooled by high efficiency blower. Should an overheating condition occur, either through component
failure or by a restricted airflow, the Amplifier contains heat sensors that will shut down the system.
As a result, the air inlet and outlet openings should be free of obstructions for proper cooling of the
amplifier. Operation is restored by the Reset button when the amplifier cools to normal temperature
levels.
4.6.2 Power Supply Faults
The Power Supply Fault circuit monitors the Helix and Collector power supplies and produces a fault
indication should any voltage level deviate from normal operating parameters. Each power supply
voltage output is monitored and displayed. Should any power supply voltage deviate from the design
parameters, the Power Supply Fault Indication LED (RED), located on the front panel of the
Amplifier will illuminate and the related fault will be displayed on the LCD display located on the
front panel.
4.6.3 Mismatch Protection
The Amplifier is designed to operate with a tuned 50 Ohm load. Should any mismatching of the 50
Ohm load occur, the Reverse Power, also called Reflective Power, will increase, producing a high
VSWR. The Amplifier microprocessor monitors the Reverse Power levels by utilizing a Dual
Directional Coupler. When the Reflected Power exceeds 25% the Amplifier Output Power The
amplifier will go to STBY and the High VSWR message will be indicated on the LCD display. The
Reverse Power is also displayed on the LCD Display for operator monitoring for any mismatched
load.
4.7 STATUS INDICATORS, CONTROLS AND CONNECTORS
The Amplifier has various controls and status indicators which are identified below and can be
visually located on Figure 1.0, Outline Drawing and Figure 8.0, Rear Panel Illustration. A narrative
description for the function and purpose of each control and status indicator is provided within
paragraphs 4.7.1 and 4.7.2.