Setting up a Type C track circuit requires careful installation, tuning, and calibration because the system uses two separate AC frequencies for train detection and broken rail detection.
The track block is typically defined using insulated rail joints on both rails. These joints help electrically isolate the block for the signaling currents.
A dual-frequency transmitter is installed to generate both required AC frequencies at the same time. The output levels and frequency stability must be carefully adjusted.
A dual-frequency receiver is installed at the opposite end of the block. The receiver separates the two frequencies using filters and detection circuits.
Proper wiring and connections are important because poor connections or incorrect impedance can cause signal loss, distortion, or unreliable operation.
The receiver filters and detection circuits must be tuned to the transmitted frequencies. Baseline values and thresholds are established under clear track conditions.
Final testing verifies that the Type C track circuit detects train shunts, simulated rail breaks, and unwanted AC traction interference correctly.