Digital guide

You are here:
  1. Home
  2. GE
  3. GE 12SBD11B1A

GE 12SBD11B1A

  • Product Name: GE Static Bus Differential Relay, Type SBD11B
  • Product Introduction: The SBD11B is a single-phase, high-speed static differential relay specifically designed for sensitive, high-speed differential protection of buses and feeders, and for shunt reactor differential protection. It uses static circuitry to achieve very short operating times and is packaged in an S-2 drawout case requiring no auxiliary current transformers.
WhatApp
WeChat

Detailed content

  • Technical Specifications:
    • Type: SBD (Static Bus Differential)
    • Frequency: 50/60 Hz
    • Voltage Range: 50–350 V
    • DC Control Voltage: Selectable 48 V, 125 V, or 250 V DC via voltage-selecting link
    • Operating Time: Typically 5 to 8 ms
    • Case: S-2 drawout case
    • Full 3-phase protection: Requires three SBD11B relays plus one HEA lockout auxiliary relay with three normally-open contacts
  • Functional Features:
    • Sensitive, high-speed differential protection
    • High-impedance voltage-measuring circuit with overcurrent supervision
    • Phase and ground fault detection (three relays required for complete protection)
    • Breaker failure initiation when used with a suitable timing relay
    • Output isolation via telephone relay
    • Target seal-in unit
    • Drawout case for easy maintenance
  • Application Scenarios: Bus and feeder differential protection; shunt reactor differential protection; installations where severe CT saturation can occur for internal and external faults
  • Working Principle: Uses a high-impedance, voltage-actuated operating principle. Under normal conditions, the differential connection of the CTs results in negligible voltage across the relay. During an internal fault, the unbalance in CT currents produces a voltage above relay pickup, causing operation. Severe external faults — even those resulting in complete CT saturation — will not produce sufficient voltage across the relay to cause operation, ensuring selectivity.
  • Installation Requirements:
    • CTs must have fully distributed windings
    • Multi-ratio CTs may be used provided all CTs are on the same tap, yielding the same ratio
    • Relay is connected in parallel with all CT secondaries of each phase
    • Lightning arresters within the protected zone require the SBD11B2A model instead
  • Usage Notes:
    • Set the relay by calculating required voltage and current taps; select the lowest available taps that are secure from misoperation for external faults to maximize sensitivity for internal faults
    • Consult the relay instruction book for recommended setting procedures and sample calculations
    • When used with a lockout relay, the SBD11B may be used to initiate a breaker failure timer

You may also like