SEL-387 Current Differential and Overcurrent Protection Relay Versatile Solution for Power Apparatus Protection nacn utTFt events status other sci cm <*»*_ CURRENT DIFFERENTIAL RELAY OVERCURRENT RELAY data RECORDER CONTROL EQUATIONSj SCHWEITZER PULLMAN WASHINGTON ENGINEERING laboratories The SEL-387 Relay offers restrained and unrestrained differential protection for two to four 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 relay versatility. 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. A restricted earth-fault feature provides 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. Set the differential element with either a single- or dualslope percentage differential restraint characteristic for increased security during through-fault conditions. Select the optional thermal modeling element for key information about transformer overload capability. ► 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. ► Monitoring. Schedule breaker maintenance when the breaker monitor indicates. Notify personnel of substation battery voltage problems. Use the through-fault event monitor in the SEL-387-5 and SEL-387-6 for information on system through faults and the resulting, cumulative I2t wear on transformer banks. Monitor critical operating temperatures through use of the SEL-2600A RTD module. ► 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 such key information as metering data, protection elements and contact I/O status, SER reports, breaker contact wear Schweitzer Engineering Laboratories, Inc.

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 HMI provides phasor diagrams that help support commissioning and troubleshooting. The SEL-387-5 and SEL-387-6 are supported by the acSeLerator QuickSet software. Functional Overview * Optional Feature Protection Features The SEL-387 contains a variety of protective...

Operating Region I I I I I I I I I C|AnQ o Slope 2 I I I I I I I I I IRestraint Figure 2 Dual-Slope Percentage Differential Restraint Characteristic SEL-387-5 and SEL-387-6 relays guard against harmonic conditions resulting from system and transformer events that can cause relay misoperation. Use the fifth-harmonic element to prevent relay misoperation during allowable overexcitation conditions. Even-harmonic elements (second and fourth harmonic) guard against inrush currents during transformer energization. The dc element, which measures dc offset, adds to this...

Table 2 Metering Capabilities Metering Capabilities The SEL-387 provides three types of fundamental frequency metering functions: instantaneous, demand (thermal), and peak demand. Metered quantities shown in Table 2 include phase currents for all four winding inputs; positive-, negative-, and zero-sequence (residual) currents for all four 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...

breaker wear curve (Figure 4), the relay can alarm via an output contact or the front-panel display. The typical settings shown in Figure 4 are: 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 an intermediate current value providing 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-387 measures and reports the substation battery voltage...

Transformer Thermal Monitoring Transformer thermal modeling per IEEE C57.91-1995 for mineral-oil immersed transformers is an optional feature in the SEL-387. Specify the SEL-387-6 to provide this capability for monitoring and protection of a single three-phase transformer as well as for monitoring and protection of three independent single-phase units. Use the thermal element to activate a control action or issue a warning or alarm when your transformer overheats or is in danger of excessive insulation aging or loss of life. Use the thermal event report to capture current hourly or daily data...

Relay and Logic Setting Software ACSELERATOR QuickSet software uses the Microsoft Windows® operating system to simplify settings and provide analysis support for the SEL-387-5 and SEL-387-6. One can, for instance, open an ACSELERATOR QuickSet human machine interface (HMI) screen and obtain phasor information such as that shown in Figure 6. QuickSet HMI Screen Showing SEL-387 Phasor Information Use 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...