SEL-387A Current Differential and Overcurrent Protection Relay Versatile Solution for Power Apparatus Protection Major Features and Benefits The SEL-387A Relay offers restrained and unrestrained differential protection for two terminals. Second-, fourth-, and fifth-harmonic elements, augmented by the dc element, provide security during transformer energization and overexcitation conditions in a user-defined choice of either harmonic restraint or harmonic blocking. Overcurrent elements provide backup protection that contributes to the versatility of the SEL-387A. Oscillographic event reports, Sequential Events Recorder (SER), circuit breaker contact wear monitor, and substation battery voltage monitor are all standard features. Four communications ports, local display panel, and extensive automation features are also standard. Expanded I/O is available as an option. Two optional restricted earth fault elements provide sensitive protection against earth faults for wye-connected transformers. ➤ Protection. Protect transformers, buses, generators, reactors, and other apparatus with a combination of differential and overcurrent protection. The differential element is set with either a single- or dual-slope percentage differential restraint characteristic for increased security during through-fault conditions. ➤ Metering. Interrogate the relay for instantaneous measurements of phase and demand current. The recorded peak demand, including the date and time of occurrence, is provided. Use accurate metering data for system EMS/SCADA applications. ➤ Monitoring. Schedule breaker maintenance when breaker monitor indicates. Notify personnel of substation battery voltage problems. Monitor critical operating temperatures using the SEL-2600 RTD Module. Use the SEL-387A through-fault event monitor for information on system through faults and resulting cumulative I2t wear on transformer banks. Monitor critical operating temperatures through use of the SEL-2600. ➤ Automation. Take advantage of automation features that include 16 elements for each of the following: local control and local indication with front-panel LCD and pushbuttons, remote control, and latch control. Use the serial communications ports for efficient transmission of key information including metering data, protection elements and contact I/O status, SER reports, breaker contact wear monitor, relay summary event reports, and time synchronization. Select optional DNP3 Level 2 Slave protocol with virtual terminal support for SCADA system interface capability. ➤ Relay and Logic Settings Software. ACSELERATOR QuickSet® SEL-5030 Software reduces engineering costs for relay settings and logic programming. The built-in Human Machine Interface (HMI) provides phasor diagrams that help support commissioning and troubleshooting. Schweitzer Engineering Laboratories, Inc.

Overcurrent ■ Phase • Ground • Neg. Seq. 51G -Overcurrent • Phase • Ground • Neg. Seq. Overcurrent • Ground -Overcurrent Fault (REF)* • Ground Overcurrent • Phase ■ Ground • Neg. Seq. Time-Overcurrent • Phase • Ground • Neg. Seq. • SELogic® Control Equations • Event Reports • Sequential Events Recorder • Breaker Wear Monitor • Station Battery Monitor • ASCII, Binary, and Distributed Port Switch Communication • Remote and Local Control Switches • Phase, Ground, Neg. Seq., Differential, and Harmonic Metering • Restrained and Unrestrained Differential Elements • Second- and Fourth-Harmonic Blocking...

overexcitation conditions. Even-harmonic elements (second and fourth harmonic) provide security against inrush currents during transformer energization, complemented by the dc element, which measures the dc offset. The even-harmonic element offers the choice between harmonic blocking and harmonic restraint. In the blocking mode, the user selects either blocking on an individual phase basis or on a common basis, as per application and philosophy. The second-, fourth-, and fifth-harmonic thresholds are set independently, and the dc blocking and harmonic restraint features are enabled independently. An...

Table 2 Metering Capabilities Metering Capabilities The SEL-387A provides three types of fundamental frequency metering functions: instantaneous, demand (thermal), and peak demand. Metered quantities shown in Table 2 include phase currents for both winding inputs; positive-, negative-, and zero-sequence (residual) currents for both winding inputs; and operate, restraint, second-harmonic, and fifth-harmonic currents for the three differential elements. Harmonic metering provides a snapshot of harmonic current magnitudes in the phase currents, including the fundamental and harmonic components through...

The typical settings shown in Figure 4 are Set Point 1, Set Point 2, and Set Point 3. Set Point 1 approximates the continuous load current rating of the breaker. Set Point 3 is the maximum rated interrupting current for the particular breaker. Set Point 2 is some intermediate current value that provides the closest visual “fit” to the manufacturer’s curve. Figure 3 Transformer Energizing Inrush Current Plotted From Event Report Substation Battery Monitor for DC Quality Assurance The SEL-387A measures and reports the substation battery voltage presented to its power supply terminals. The relay...

Relay and Logic Setting Software The ACSELERATOR QuickSet software uses the Microsoft® Windows® operating system to simplify settings and provide analysis support for the SEL-387A. One can, for instance, open an ACSELERATOR HMI screen and obtain phasor information similar to that shown in Figure 5. SEL-5030 HMI Screen Showing SEL-387 Phasor Information Use the ACSELERATOR QuickSet software to create and manage relay settings: ➤ Develop settings off-line with an intelligent settings editor that only allows valid settings. ➤ Use on-line help to assist with configuration of proper settings. ➤ Organize...