Self-adjusting Receiver

This unit is pin-for-pin compatible with the previous TC-10B/ TCF-10B design, performs the same functions, and is easier to adjust! This enhancement with backward compatibility is proof of our commitment to stay on the leading edge of Power Line Carrier technology for our customers' benefit. 

Receiver Features:

• Digital Signal Processing (DSP) Technology. Considerably reduces number of components for greater reliability. Switches select bandwidth for TC-10B and TCF-10B and shift for the TCF-10B receiver. 
• Automatic adjustment of receiver margin to 15 dB, ± 5 dB in 1 dB steps via front panel accessible pushbuttons. This greatly reduces setup and maintenance time and the possibility for errors
• Continuous four digit LED frequency readout. 
• Carrier level indicator uses easy-to-read LED bargraph display. 
• Frequency programming uses front panel accessible pushbuttons over a 30-535 kHz range without changing filters. Permits setting frequency without removing the module or purchasing filters. 
• No instruments required to set the receiver module. 
• One module replaces two modules (Receiver/Detector & CLI for TC-10B or Receiver/Discriminator & CLI for TCF-10B). 
• Front end analog and digital filtering provides superior bandwidth selectivity. 
• Optimum receiver sensitivity maintained.
• Fits into existing chassis, even those shipped under the Westinghouse or ABB nameplates. 
• Older receiver units easily upgraded in the field.

New Voice Adapter

• Works with new Self-Adjusting Receiver. 
• Works with old voice adapters at remote end of line. 
• Improved voice quality over previous versions. 
• Built-in signaling alarm for ringing.

Directional Comparison Unblocking

The basic elements of Directional Comparison Unblocking systems include phase and ground distance or directional overcurrent relays (21P, 21NP, or 67NP) and a frequency-shift keyed (FSK) carrier channel. The pilot relays are set to reach 120 to 150 percent of the protected line. The FSK channel is normally transmitting guard frequency at a 1 watt power output. The guard frequency is continuously monitored to detect channel trouble early before it is needed to respond a system fault. 

For an internal fault, pilot relays at both ends will operate, shifting the transmitters from "guard" to "unblock" and boosting power output up to 10 watts. Tripping is initiated when the local pilot relays are picked up and the unblock frequency is received. These two conditions are never met for an external fault since the local pilot relays only operate for faults in the direction of the protected line and the unblock frequency is not transmitted from the remote terminal. A trip window is provided to allow high-speed tripping for an internal fault that shorts carrier to ground, preventing receipt of the unblock frequency. For 150 ms after a loss of carrier is detected, the pilot relays are permitted to trip without receiving the unblock frequency. After the 150 ms window, high-speed pilot tripping is blocked until the channel status is returned to normal.

The dependability and security of the Directional Comparison Unblocking system makes it the most attractive of the protective schemes for transmission lines using power-line carrier channels. Tripping for internal faults is insured by the 150 ms trip window. Proper tuning and maintenance of the connected line tuners, spark gaps and traps insures blocking of pilot tripping for close-in external faults.

The scheme can also be applied to multi-terminal lines. Each terminal is assigned a unique transmitter frequency and each terminal must have multiple receivers to detect all other terminal transmitter frequencies. High-speed tripping is initiated when a terminal receives unblock frequencies from all other terminals and the pilot relay sees the fault.

Phase Comparison Unblocking

The TCF-10B can be utilized in two types of phase comparison schemes: Dual Phase Comparison and Segregated Phase Comparison. In both schemes the relay keys the transmitter between two frequencies to convert the power signal to a square wave. When this square wave is received at the remote terminal, it is compared with its local signal to determine if the fault is internal or external to the protected line.

To obtain the highest fault clearing time, the wide-band receivers (600 or 1200 Hz) are normally used. In cases where frequency spectrum or noise is a problem, narrow-band receivers (300 Hz) may be used.

Direct Transfer Trip

The TCF-10B carrier can be applied for transformer or breaker failure protection in a Direct Transfer Trip (DTT) scheme where remote clearing of faults is necessary. Since receipt of trip is not supervised by a fault detecting relay it is normally configured as dual-channel, requiring a received trip from both channels to initiate tripping. Narrow-band filters are normally used to reduce sensitivity to channel noise thereby increasing the likelihood that a trip will be received during high-noise conditions which are typical during a fault. The slightly increased channel time caused by the narrow-band filter is generally an acceptable trade-off for more reliable tripping. The carrier can be applied in a uni-directional mode with transmitters at one end and receivers at the other. Transceivers at both ends are applied when bi-directional t