Overcurrent Controls for Vacuum Fault Interrupters

Vacuum Interrupter Operation
The overcurrent control monitors the current and sends a trip signal which opens the vacuum interrupters and interrupts the fault current.  The control is self-powered by current transformers located inside the sealed switch tank.  The user elects the time-current curve (TCC) desired.  Remote trip and remote power connections are available as an option.

Control Enclosures
Standard control enclosures are NEMA 4X (IP56) rated and are mounted inside the padmount enclosure.  Optional submersible enclosures are NEMA 6P (IP67) rated.

Type 1

Type 1 controls three, single phase vacuum interrupting mechanisms.   The Type 1 can be field set for either single phase or three phase trip mode.  It is used on switches with either single phase reset or three phase reset.  When in three phase mode, all three phases trip if the control trip level of any individual phase is reached.  Trip level selections can be made under load or no-load conditions with current ranges in 12 selectable levels.  Two ranges of minimum trip settings are available, 15 to 300 amps and 30 to 600 amps.  Each unit is preprogrammed with multiple TCCs.  The curve selection can be set or changes at any time.

An 8 pole dip switch allows the user to choose the TCC that best matches their individual coordination requirements.  A label, located on the inside of the lid, provides a key for the dip switch settings.  The control can be factory preset to meet the user's requirements.  As protection or coordination requirements change, settings can easily be changes in the field.  Depressing the manual trip button when the control is powered up electronically trips all three phases of the vacuum interrupter.  Each control also includes "Last Cause of Trip" LEDs.  These LEDs indicate which phase experienced an overcurrent condition, or that the control was given an external or manual trip command.

Type 2

Type 2 controls offer features similar to Type 1 with the following exceptions:

• Three phase protection only
• Minimum trip set for all three phases with one selector switch
• Manual trip button for manual tripping of all three phases
• Adjustable phase time delay
• Ground fault (phase imbalance) feature with separate adjustable time delay selector switch for protection of large three phase motors or transformers. The ground trip level is represented as a percent of the minimum trip level.
• Instantaneous trip and inrush restraint features

Type 3

Type 3 controls offers features similar to Type 2 and more including:

• Single phase or three phase trip

• Vacuum fluorescent display
• Keypad operation for programming parameters and retrieving status of current values
• Multiple TCC curve capability
• Adjustable phase time delay
• Ground fault trip
• Inrush restraint
• Phase identification and magnitude of fault indication
• Readout of real-time values
• Selectable instantaneous trip
• Selectable minimum response time
• RS232 or RS485 serial interface
• Laptop programming kit available

Type 4

Type 4 controls provide the same features as Type 3 however, there is no keypad panel, display screen, or manual trip button. The electronics are mounted external in a separate enclosure. The control is programmed using a laptop computer. A laptop programming kit is available.