SEL -300G RELAY PROTECTION APPLICATIONS Complete Generator Primary Protection When ordered with the optional differential elements, the SEL-300G provides a full complement of primary protection elements for large machines. The relay is built on the field -proven SEL -300 Series Relay platform, known for secure, dependable, high -performance protection. DWG: M300G028SEL-387Unit DifferentialSEL-300G1PrimarySEL-300G0Backupor Figure 1. 1: Large Generator Primary and Backup Protection In these applications, three - or four -wire potentials and three -phase currents are applied to the relay for principal protection and metering functions. When differential protection is included, three addi tional phase current measurements are required. Neutral voltage for 100 percent stator ground protection is taken from the secondary of the grounding transformer. The SEL-300G neutral voltage input is rated for application up to 300 Vac, which means that, for most applications, an auxiliary voltage transformer will not be necessary between the grounding transformer secondary and this relay. In applications where neutral overcurrent protection is desired, the SEL-300G neutral current input, IN, may be conne cted to the secondary of a neutral current transformer. This transformer may be located in the generator neutral or connected in the secondary circuit of the grounding transformer. In solidly grounded or resistance grounded applications, the SEL -300G0 an d SEL-300G 2 chuyển tiếp đất vi sai (87N) cung cấp bảo vệ.
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