L-828 CCRs LC-Type (4, 7.5, and 10 kW/6.6 A/60 Hz)

Description

4.Theory of Operation Introduction

Silicon Control Rectifiers (SCRs)

This subsection describes the L-828 CCR theory of operation.

Current regulation is obtained by using SCRs to switch the supply power (by varying the On duration of the AC cycle) to the power transformer and by using feedback circuitry to monitor the transformer’s output. The brightness level is selected from one of three or five preset values. Load variation is detected as a change in the control voltage by the controller. The controller changes the conduction angle of the AC voltage to the SCRs to adjust the power flow into the power transformer. This sequence of events compensates for the load variation and maintains the output current at the preset level.

See Figure 8-1 in the Wiring Schematics section. When power is applied to the CCR at TB3 terminals 1 and 2 and the contactor K1 and circuit breaker CB1 are closed, no current will flow in the primary of the power transformer T1 until the silicon control rectifiers (SCRs) receive a trigger pulse. When this pulse occurs, the SCRs turn on. This allows the current to flow into the primary of the power transformer T1 until the SCR is switched off by the zero crossing of the input voltage.

The path of the current flow is from TB3-2 through the circuit breaker CB1, contractor K1, SCR1 terminals 1 and 3 to L2, L1, and primary of T1, and back to K1, CB1, and TB3-1. Since alternating current is used for the regulator operation, after zero-crossing the current flows in the opposite direction using the other SCR (see SCR1 terminals 1 and 2).

The power level in the primary of the power transformer is controlled by varying the phase of the conduction angle. If very low output current is desired, the conduction angle would be near zero degrees, that is, the SCR is not triggered until the input voltage is near zero- crossing. Little power is then available to power transformer T1.

For maximum power to occur in the primary of the power transformer T1, the conduction angle will be near 180 degrees. Immediately after zero-crossing of the input power sine wave, the SCR is triggered and operates continuously throughout the 180- degree duration of the input sine wave.

For 67% power from the power transformer, the conduction angle will be nearly 90 degrees. This occurs approximately at the voltage peak of the sine wave when the SCR switches into conduction.

Switching the transformer on-line at this time creates a rather abrupt rise time, since the sine wave is at its peak voltage. Choke L1 slows this rapid rise time from the conduction of the SCRs.

2002 Siemens Airfield Solutions, Incorporated

96A0104B

Page 2-4

All rights reserved

Issued 6/02

 

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Siemens L-828 manual CCRs LC-Type 4, 7.5, and 10 kW/6.6 A/60 Hz Description
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L-828 specifications

The Siemens L-828 is a state-of-the-art aircraft communication and navigation system that is designed to enhance efficiency and safety in aviation operations. This system is equipped with a range of advanced features that cater to the evolving needs of modern air traffic management and avionics.

One of the standout characteristics of the L-828 is its versatile communication capabilities. It incorporates VHF and UHF radio systems, enabling flexible and reliable communication between pilots, air traffic controllers, and other aircraft. The system supports both voice communication and data link services, ensuring that critical information is exchanged seamlessly during flight operations.

In terms of navigation, the Siemens L-828 is equipped with cutting-edge Global Navigation Satellite System (GNSS) technology. This allows for precise positioning and navigation, essential for modern pilotage in complex airspace environments. With built-in performance monitoring, the system can also provide predictive analytics, which enhances situational awareness for pilots and ground controllers.

The architecture of the L-828 is designed for ease of integration with existing aircraft systems. Its modular design allows for straightforward upgrades and the incorporation of additional functionalities as aviation technology continues to evolve. This adaptability ensures that operators can extend the lifespan of their investment by easily implementing new features without requiring a complete system overhaul.

Another key feature of the Siemens L-828 is its robust cybersecurity measures. In an era where the threat of cyberattacks is growing, the system employs advanced encryption techniques and authentication protocols to safeguard sensitive communications and data. This emphasis on security ensures that both operational integrity and passenger safety are maintained.

Moreover, the Siemens L-828 has user-friendly interfaces that reduce pilot workload and enhance overall flight experience. With intuitive controls and clear displays, pilots can easily access critical information, thereby facilitating smoother and safer flight operations.

In conclusion, the Siemens L-828 represents a significant advancement in aviation communication and navigation technology. Its combination of versatile communication capabilities, advanced navigation systems, modular design, and heightened security protocols makes it a crucial tool for modern aircraft. As the aviation industry continues to evolve, systems like the L-828 will undoubtedly play an indispensable role in optimizing flight operations and ensuring safety in the skies.
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