Basler Electric BE1-50 - Manual (Page 9)

SECTION 1 • GENERAL INFORMATION
PURPOSE
Instantaneous overcurrent relays provide phase and ground fault protection for distribution circuits,
generators, motors, transformers, and other major components of power systems. BE1-50 Instantaneous
Overcurrent relays have a wide range of pickup settings and input configurations to accommodate
protection requirements for power systems. BE1-50 relays are available in single or multi-phase for power
units.
APPLICATION
Some applications are illustrated in Figure 1-1.
Figure 1-1. Typical BE1-50 Applications
Ground Fault Detection
BE1-50 relays can be applied to monitor zero sequence currents that are indicative of ground faults. The
most sensitive method of ground fault protection utilizes a single current transformer through which all the
conductors are passed (Figure 1-1b). Another method uses the residual connection of the three-phase
CTs (Figure 1-1d) with the relay set higher than the normal system unbalance. The most direct method is
to place a CT in the neutral of a grounded wye connection for equipment such as power transformers or
generators (Figure 1-1c).
Phase Fault Detection
BE1-50 relays can be used in two ways to detect phase faults. The first method is to place an
instantaneous overcurrent element in each phase with the setting higher than expected load current for
any power system element (Figure 1-1a, d, e, f). The second method is called self-balancing differential
protection (Figure 1-2).
9171000990 Rev F BE1-50 General Information 1-1