Substation Automation

Bus Protection Panel

Busbar Protection Panel

Sanion’s 154kV busbar protection panel, which is developed and manufactured by pure domestic technology, consists of multiple bay units (BU) which monitor the current of each feeders connected to the busbar and collect status information of circuit breakers and disconnecting switches. It also consists of a central unit (CU) which performs current differential protection by using the current values and status information received from the bus. In addition, CU measures the voltage of each busbar to use it for fault detection.


  • A busbar is one of the power system facilities in the substation, which concentrates and re-distributes electric power by connecting transmission lines and transformer banks. In case of a busbar fault, the fault current is very large. If the fault learing gets delayed, it migt be extended to a much wider range of faults.

    There are various types of busbar structures such as radial type, ring type or double type busbar. Among these types, double busbar is most widey used because it is able to shorten fault duration and provide high reliability and good maintainability. In particular, 345kV class adapts 1.5CB structure in which 3 circuit breakers are placed between the two busbars. 154kV busbar protection panel provides current differential protection function to ensure fast and accurate fault detection in a double busbar structure and to isolate faults and safely protect the busbar.

    Busbar protection function is internally divided into the separate zone (zone 1 or 2) protection to detect busbar with a fault. The entire busbar protection detects which part of the busbar has a fault. For example, if both entire busbar protection and separate protection for zone 1 detect a fault, the busbar protection function determines that a fault has occurred on No. 1 busbar.

Main functions

  • Main functions of central unit (SBP-K110-CU)
    • Phase-segregated current differential protection (87B)
    • Undervoltage based fault detection (UV/UVS/UVD)
    • Overcurrent protection (50BF) for circuit breaker failures
    • CT and PT failure detection and alarming
    • External fault detection to prevent wrong tripping due to CT saturation
    • Busbar-bridged protection according to the status conditions of DS's and alarming for abnormal conditions
    • Automated compensation for different CT ratios
    • Communication with multiple BUs based on high speed serial communication (1Gbps, fiber optic)
    • Fully IEC 61850 compliant, Edition 1
    • Self-monitoring on a regular basis
  • Main functions of bay unit (SBP-K110-BU)
    • Current measurement and status monitoring of CB, DS and BFI for two feeders
    • Communication with CU based on high speed serial communication (1Gbps, fiber optic)
    • Self-monitoring on a regular basis


Division Item Specification
Ratings Input power DC 90~140[V],60Hz DC 90~140[V],60Hz
Rated voltage(PT) 110/√3[V] -
Rated current(CT) - 5[A]
Digital output 10[A] : 250VAC
24 points
10[A] : 250VAC
14 points
Digital input DC 70 ~ 150[V]
24 points
DC 70 ~ 150[V]
24 points
Communication Communication port RS-232, Ethernet, Fiber Optic RS-232, Fiber Optic
Protocol IEC61850, TCP/IP -
Time sync. IRIG-B, SNTP -