S&S has been manufacturing distribution switches such as Load Break Switches, Auto Section Switches, High / Medium Voltage Switches and Pad Mounted Switches. Based on the accumulated technology in the field of electric power distribution, S&S is trying to gain customers’ trust through its incessant development in new technology and lasting investment in facilities.

 


                
 
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Control Unit for motorized SF6 Load Break Switch



Control Unit for motorized SF6 Load Break Switch
 
 
Control unit was designed to work locally and remotely with motorized type SGS Load Break Switch for overhead lines. It can communicate with SCADA or DAS via RTU and MODEM.

Product Highlights
   - Control cubicle is fabricated from stainless steel sheet of not less than 2 mm in thickness
     and suitable for mounting on a pole through a steel channel fixed to the back of the cabinet
     for mounting purpose. It has the characteristics for good thermal insulation, ventilation and
     water penetration, and is installed with grounding terminal connector and padlock etc.
   - Electrical surge protection and impedance-matching control circuit board is constructed and
     tested to meet the latest applicable standards of IEC 60255 and ANSI/IEEE C37.90.1.
   - Lead acid battery provides DC power to the local control circuit board in case of AC power
     source failure. The battery has sufficient capacity to sustain more than 24 hour operation
     while AC power supply’s failure, with a minimum lifetime of 3 years.
     The battery is automatically disconnected from the control circuit when the battery voltage
     falls below a preset value in order to prevent deep battery discharging.
   - Auxiliary power cable and control cable with outdoor-rate connectors at each end to
     connect the mating receptacles on the load break switch and on the bottom of the control
     cabinet. The control cables are shielded from electromagnetic interface(EMI) and radio
     frequency interface.

Power Supply
   - AC power supply from power source inputs 220VAC to the control unit, and DC power
      24VDC is parallel connected with battery and the other part of the control circuit.
   - Battery charger has trickle charging mode and protecting function of over charging.
      Battery : lead acid battery 18Ah and 24VDC input toward control circuit.

Local Control Circuit
   - 3 CT signal(1000 : 1, but other ratio selectable) and 6 voltage signal output(4 VAC output but
     other value available) from the load break switch.
   - Battery testing to check the battery voltage on load condition & battery charger.
   - Local/Remote control selection switch.
   - Local close/open button.
   - Separate Open(green) and Close(red) status LED.
   - Low gas pressure status LED.

RTU for remote control (option)
   The RTU can be supplied to communicate with center control, to measure the electrical
   quantity, and to get the fault information.
   It is using the DSP for calculation and micro-processor for other tasks. It can measure the
   V, I, VA, W, VAR and power factor, detect the fault current and memory the wave form for
   further analysis.

   - Hardware
   □ Total 14 status monitoring points
      Open / Close / Earth status
      Lock / Unlock status
      Local / Remote status
      Gas pressure status
   □ Total 9 measuring input points
      3 Current of each phase
      6 Voltage of each phase
   □ Total 8 control output points
      Open / Close control signal
      Lock / Unlock control signal
      Battery test control signal

   - Measurement
   □ Instantaneous metering
      Currents          I / a,b,c,n input current
      Voltages         V / a,b,c wye-connected voltage inputs
      Power            MW / a,b,c mega-watts(wye-connected voltage inputs only)
                           MVAR / a,b,c mega-vars(wye-connected voltage inputs only)
      Power factor   PF / a,b,c power factor : leading or lagging
   □ Demand metering
      Currents          I / a,b,c,n input currents
      Power            MW / a,b,c mega-watts(wye-connected voltage inputs only)
                           MVAR / a,b,c mega-vars(wye-connected voltage inputs only)
   □ Max. / Min. metering
      Currents         I / a,b,c,n input currents
      Power          MW / 3p 3 phase mega-watts
                         MVAR / 3p 3 phase mega-vars

   - Events
   Many kinds of events with time tags are useful for analysis of the switch, RTU, communication
   and power line.
   □ Power - on / off
   □ Ext. Power - on /off
   □ Self testing result
   □ Change the settings
   □ Switch - close / open (remote/local communication port)
   □ Lock / Unlock
   □ Low gas
   □ Low battery
   □ Line voltage - on / off, source side / load side
   □ Fault - pick up / drop out
   □ Phase discord
   □ One or two loss of line voltage

   - Fault Indicator
   The fault information is used for identifying the faulted section. It has the special logics to
   distinguish the temporary fault and permanent fault.
   □ Inrush restraint feature ; If the current changes from normal current to 0 current, then
      it blocks the pick-up within preprogrammed time.
   □ Pre-detecting time(software programmable) ; If the over current condition lasts more than
      this time, it is validated as the start of a potential fault.
   □ In progress ; It memories the current, voltage, wave form until the over current condition
      finishes, and it takes the maximum rms fault current.
   □ Final ; If the over current condition is finished and the current goes to 0 (back up protection
      device clears the fault) or goes to normal current (forward protection device clears the
      fault), it waits the maximum reclosing interval of back up device, and when the programmed
      time elapse it finally decides whether the over current was temporary or permanent fault.
      Every effective over current condition is recorded as the events and the final temporary or
      permanent fault information is recorded as fault indicator information.
      It consists of start time, fault current level, end time, number of over load conditions and
      temporary or permanent fault information. The fault indicator can check the forward fault or
      reverse fault to give the correct fault information.

   - Communication Ports
  
PORT 1 MODEM DNP 3.0 level 2
 Communication rate  9600 bps(programmable)
 Interface  RS-232C
PORT 2  Notebook
 Communication rate  19200bps (programmable)
 Interface RS-232C
 
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