TRENDnet BE1-87G - Manual (Page 14)

BE1-87G - Functional Description 3-1
SECTION 3 • FUNCTIONAL DESCRIPTION
GENERAL
BE1-87G Variable Percentage Differential Relays are static devices that protect motors and generators by
providing an output signal when incoming current does not match outgoing current by a predetermined but
variable limit. The functional block diagram in Figure 3-1 illustrates the overall operation of the BE1-87G
Variable Percentage Differential Relay. Note that it may be configured to monitor either single-phase or three-
phase. Phases B and C, when present, are functionally identical to Phase A.
Figure 3-1. Functional Block Diagram
FUNCTIONAL DESCRIPTION
The following paragraphs describe the Relay circuit functions illustrated in Figure 3-1.
Current Transformers
Two standard system CTs with secondary windings to match sensing input range one or range two (five ampere