Transformer Protection

		SEL-387 Current Differential and Overcurrent Relay Use the SEL-387 Relay for protection, monitoring and automation applications for important transformers, generators and other power apparatus. Apply one SEL-387 Relay to protect any two-, three- or four-winding power transformers. Detect ground faults through D/Y transformer banks, or provide sensitive phase-to-phase protection independent of load current, with negative-sequence overcurrent element. Unrestrained high-set differential elements provide fast operation for high-magnitude internal faults. "Around-the-clock" phase angle compensation settings and automatic tap calculations simplify settings.
		SEL-587 Current Differential Relay Provides inexpensive differential protection for two-winding transformers or other two-terminal apparatus. Individual winding phase, residual and negative-sequence overcurrent elements, including instantaneous, definite-time and inverse-time overcurrent elements for comprehensive overcurrent protection. Detect ground-faults through D/Y transformer banks, or sensitive phase-to-phase protection, independent of load current, with negative-sequence overcurrent element. Protect any two-winding power transformer. Apply with any combination of D/Y-connected CT secondary circuits.