Moscad / Darcom


Test Technicians


Instrument Control



Test Technicians

Relay Test Technicians:
Key Benefits:
  • All TRC Relay Test Techs have at least 15 years experience.
  • All have been trained by the major Power Utilities.
  • Extensively Trained in Safety Procedures for High Voltage

Our staff of skilled Relay Test Technicians will inspect, test and evaluate your protective relay schemes and make recommendations to optimize reliability.

Electric Transmission Substation:
TRC Relay Test Techs provide testing and start-up services on electric transmission substation equipment. These services included field engineering, testing of electro-mechanical and microprocessor based relays, functional tests, and on-site supervision.

Synchronous machines, Motors & Transformers:
Test and inspection of synchronous machines, motors, transformers, voltage regulators, instrument transformers, circuit breakers, cables and other apparatus used in the generation, transmission and distribution of electricity.


  • Directional Comparison Relaying & Power Line Carrier
  • Power System Analysis and Coordination
  • Electrical Apparatus Testing
  • Testing Microprocessor Based Relays
  • PC Based Automated Relay Testing
  • Use of Lockouts and Lockout Tags

Contact Test Technicians
Crew 1 - Jack Gregg, James Anderson, Thomas Walley, Lanny Hethcox
Crew 2 - Richard Corbell, Michael Corbell, Richard Morris
Crew 3 - David Lopez

Switchgear Solutions and Retrofits:

Huntington Beach Generating Station, Huntington Beach CA. an AES LLC independent power producer

Replace the old 4,160 AC volt inter-tie Circuit Breakers that tie the reserve busses between Units 1 and 2 to Units 3 and 4

Used one SEL-351S relay for each Circuit Breaker

Used the mirrored bit communication capability of the SEL-351S to automate the system

Used an SEL-2100 for mirrored bit communication between relays and to communicate to the station DCS used an SEL-2020.

The transfer scheme operation for the Inter-tie switchgear will trip, close, auto transfer, block closing and auto transfer Via the SEL-351S relays. There are three "Auto-Manual" switches in the control room one for each breaker to select which breakers can perform the automatic transfer. Normally all 3 breakers would have the switch in the Auto mode.

Breaker #1 is for Unit 1, 4160 volt bus, #2 is for Unit 2, 4160 bus and #3 is for the Reserve bus. It is possible to manually operate all 3 breakers one at a time with the automatic transfer scheme auto and also select which breaker is transferred to during any auto transfer. Breakers #1 and #2 are the main sources of power for the Inter-tie feeder. Breaker #3 is the last resort source. Each breaker SEL-351S relay is checking all 3 breakers for breaker open or closed status, Auto Manual status, fault trip conditions, unit power availability and for under voltage on the Inter-tie or unit bus. In addition the Sel-351S relays will perform sync check close and dead Inter-tie transfers.

The transfer scheme will be initiated following a 3 cycle delay after the inter-tie bus voltage experiences an incursion into the UV transfer window (85% to 80% of nominal). The transfer scheme is blocked from operating at below 80% of nominal volts, assumed to be 4200/120. The reserve source should only be used if Unit 1 and 2 are not available. Unit 1 would be the preferred source, if available and Unit 2 would be the alternate source if available and Unit 1 is unavailable. The logic on each relay is identical when deciding to close its own breaker. The difference is in deciding which breaker to close or to which unit to transfer.

An external trip causing a dead inter-tie and dead Unit Bus with an open breaker will cause a transfer. A dead inter-tie and a dead unit bus with the breaker closed will not cause a transfer and will lockout the automation program after a short time delay. An internal trip from an SEL-351S relay will lockout the automation program until the target is reset on the Unit that relayed. An internal trip from the 351S relay with a “breaker-fail-to-trip” condition was not addressed for this installation. That circumstance should have been addressed in the existing upstream external protection.

If the inter-tie is energized from units 3 & 4 with unit 1, unit 2 and the reserve unit CB’s open, buses energized and the relays not locked out, the system would sync and close into the first unit that is made auto. The System doesn’t communicate with units 3 & 4. The sync function of the 351S relay will not allow anyone to close its associated breaker unless the systems are synchronized.

After an inter-tie protection internal trip from SEL-351S relay the auto operation is locked out in all three relays. The reset for this lock out is the target reset button of the relay that sensed the trip current. Pushing the target reset will restore the programs to normal operation. Pressing the target reset button resets all latches in the program.

This project was a challenge because it had to be done with out interrupting the normal day to day operation of the station. As all challenging projects it was satisfying to see it through to completion. I have gained much experience in the area of SEL relay mirrored bit programming.


The LPS is a multi-function digital protective relay system intended to provide distance protection for transmission lines. It may be also applied where system backup is required. It is available for single or three phase tripping applications. Typical operating times are within 1 cycle.


  • Distance protection for transmission lines
  • High speed tripping
  • Protection and Control

  • Four zones of distance protection
  • Pilot protection, step distance backup
  • Out of step blocking
  • Phase instantaneous overcurrent
  • Ground instantaneous overcurrent
  • Ground time overcurrent backup
  • Over and under voltage functions
  • Configurable inputs and outputs
  • Monitoring and Metering

  • Integrated metering
  • Fault location
  • Event reporting of last 100 events
  • Fault reports
  • High resolution oscillography
  • User Interface

  • LCD display and keypad
  • RS232 and RS485 serial ports
  • ASCII or GE protocols

  • Location
    The High Desert Power plant in Victorville, California, is a state-of-the-art electric generating facility and one of the first major power plants built in Southern California since the early 1990s. It produces 830 megawatts of energy, enough to power 800,000 typical California homes.

    Accepted, programmed and tested the GE ALPS the SEL-311C relays and the RFL communication gear, for the scheme that protects the SCE Company inter-tie line to Victorville Substation.

    The SEL-311C Protection is an advanced, full-featured, three-pole trip/reclose relay for transmission protection applications. A powerful suite of phase and ground protection elements coupled with out-of-step blocking.

    The LPS is a multi-function digital protective relay system intended to provide distance protection for transmission lines. It may be also applied where system backup is required. Typical operating times are within 1 cycle.

    This relay scheme and its fiber optic communication channel protest’s the Victorville-Coldwell 220KV line via the permissive over reaching transfer tripping function. Each relay is a stand alone line protection relay.