Generator Paralleling Switchgear

Generator Paralleling Switchgear

Automatic Paralleling Switchgear Low & Medium VoltageAPTView SCADA Control Panel HMI

APT Automatic Paralleling Switchgear can be used in Prime Power or an Emergency Power applications which requires operation of multiple generators in parallel.

Automatic Paralleling Switchgear Features:

  • Available in Low Voltage (UL891 listed) or Medium Voltage (UL Metal Clad)
  • Integrated Microprocessor Control
  • Completely automatic operation
    • Automatic Paralleling
    • Remote Start/Stop Interface
    • kW and kVAR Load Sharing
    • Load Shed Control
  • Optional SCADA-ready Modbus Comm Port for Monitoring and Control
  • Standard Silver Plated Copper Bus
  • Inhibits Closing of Multiple Generators to a Dead Bus Simultaneously
  • First Up – First On Logic Connects First Available (which builds up voltage and frequency) to a Dead Bus

PDF Icon APT Automatic Generator Paralleling Switchgear Spec Sheet

DOCX Icon APT Automatic Generator Paralleling Control System Specification Word Document

Operation Overview


Upon receipt of an automatic start signal initiated locally by the operator or remotely by customer’s SCADA RTU (via closure of a dry contact), the switchgear shall issue a start signal to the generator set. At that time, generator set’s speed shall be controlled by the switchgear. Generator voltage shall be determined by the voltage adjust potentiometer. If the bus is dead and other conditions are appropriate, then the first generator to build up voltage and frequency shall close its synchronizing circuit breaker, energizing the bus. If the load bus is already energized, then the generator set shall be automatically synchronized with the load bus under the supervision of the dedicated synchronizing check relay. When all the synchronizing conditions are met the synchronizing circuit breaker shall close. At that time, the generator set shall operate as an isochronous load sharing machine. Real load (kW) and reactive load (kVAR) shall be shared proportionally with other generator sets connected to the load bus.

Upon receipt of an automatic stop signal initiated locally by the operator or remotely by customer SCADA or DCS system (via closure of a dry contact) the switchgear shall automatically open the circuit breaker and shutdown the generator set after a cool down period.

The switchgear shall also include provisions for manual operation.

Load Shed Control Equipment


In case of bus overload multiple stage load shed capability shall be provided. Non critical loads feeder circuit breakers shall be tripped and/or form “C” dry type contacts will be provided for each stage of load shedding to disconnect non critical loads downstream from the switchgear.

Load shed ON – OFF/RESET switch shall be provided as part of the system.

Time delays for each stage of load shed shall be adjustable through the operator interface unit mounted on the door.


Installation Diagrams

PDF Icon APT Typical Wiring Diagram
PDF Icon 5/15kV Switchgear Outline
PDF Icon 5/15kV Switchgear Floor Plan
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PDF Icon 15kV Neutral Gnding Resistor
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PDF Icon 54″ Deep Low Voltage Switchgear (Arrangement #1)
PDF Icon 54″ Deep Low Voltage Switchgear (Arrangement #2)
PDF Icon 46″ Deep Low Voltage Swgr
PDF Icon 23.5″ Deep Control Cabinet
PDF Icon 31.5″ Deep Control Cabinet