Automatic Throw Over Systems

Improve Power System Reliability

Transfer Utility Controllers
POWER MANAGEMENT Transfer Utility Controllers are ideally suited to retrofit existing manually operated power equipment supplied by multiple utility sources. Used in conjunction with Circuit Monitors, the Transfer Utility Controller’s built-in control logic seeks the utility source with good voltage, isolates the faulted circuit, and sends signals to control electric operated circuit breakers to keep the electrical system operational. Both the Main - Main and Main – Tie – Main Transfer Controllers provide a manual and auto mode with adjustable source fail, source restoration and open/closed transition time delays. Although designed primarily for automatic unattended operations, the manual operation is hard-wired and does not rely upon the PLC to ensure maximum system reliability. The POWER MANAGEMENT Transfer Utility Controller engineered solution also comes complete with sequence of event recording (SER) and diagnostics of system inputs/outputs.

  • Designed by MeterlogicInc – a company experienced with power equipment and implementing transfer schemes
  • Standardized solution with complete documentation
  • Design based on industrial rated MODBUS PLC with industry defacto standard MODBUS protocol for compatible and open system compatibility
  • Provides user access to transfer program and time delays
  • Controller PLC compatible with POWER MANAGEMENT monitoring system that provides web-enabled access information via remote PC
  • MeterlogicInc has nationally recognized Power System Engineering resources available for system design, power quality and energy management assessment, and code compliance analysis
  • Provides remote alarm notification to pagers and historical SER information
  • Complete solution – system study, turnkey installation, system integration and startup

Custom Auto Throw Over (ATO) Systems
MeterlogicInc engineers are also capable of providing advanced power reliability systems with sophisticated transfer schemes that include system integration to retrofit power monitoring and control with automatic switching between Utility or Generator sources or Generator Paralleling with system control.

Example Automated Sequence Descriptions:
a. Dual Utility Outage Less Than 4 seconds: METERLOGIC ATO system will start generators after an undervoltage condition less than 90% for 0.5 seconds is sensed at the MSB mains. At t=2, utility reclosers perform a one-shot reclose. At t=3, utility switching gear will begin transferring to the alternate source. At t=4, the transfer to the alternate source is complete. If power is restored to the MSB main, generators start, but, no transfers are initiated. Generators run unloaded for a predetermined time, and then go thru a "cooldown" cycle.

b. Dual Utility Outage Greater Than 4 seconds: METERLOGIC ATO system should open all MSB breakers. Since the A side generator-life-safety breaker is normally closed, the life safety ATS will transfer to the generator source as soon as the source becomes available. This will restore life safety power to the facility within the 10 second code requirement. After both generators have come up to speed, voltage and frequency, the generator input to the respective MSB should be closed (t=12), and the load add sequence should be enabled to gradually step the load onto the generator bus.

c. Single Utility Outage detected by an under voltage condition less than 90% for 0.5 seconds, the METERLOGIC ATO system should open the affected side utility main and all its feeder breakers. Then give a generator start signal to both generators. After both generators have come up to speed, voltage and frequency, the generator input to the affected MSB should be closed, and the load add sequence should be enabled to gradually step the load onto the generator bus. The unaffected generator can be shutdown after the other generator successfully restores power to it’s side. After utility power returns, the ATO system will monitor the returned source and then open the generator input and close the utility main. After a (5) minute cool down, the generator can be stopped.

Example capabilities:

  • Synchronization and paralleling of two generators
  • Monitoring of two utility feeds with the ability to island if necessary
  • Shedding of approx. 50 non-critical loads to avoid any single source becoming overloaded.
  • SCADA interface via Power Management Software used for load transfer and generator start/stop
  • If utility source fails, generator is started, and load transferred to generator
  • Hot standby PLC