Basler Electric BE1-50/51B-231 - Manual (Page 15)

9252000895 Rev C BE1-50/51B-231 General Information 1-5
Instantaneous characteristic curves are similar to standard electromechanical instantaneous units.
However, the time to trip for applications where the initial current through the relay is less than 0.4
ampere may be slightly longer. This may occur on a very lightly loaded circuit or when the relay is
providing ground protection and is connected to measure neutral current.
Curve Characteristics
Figure 1-2 shows the
instantaneous characteristic curves for maximum time to trip.
An additional fixed delay of 0.1, 0.2, or 0.3 second may be added with internal switches SW3-1 and
SW3-2. This delay applies to both phase and ground applications. Closing switch SW3-1 provides an
additional delay of 0.2 second. Closing switch SW3-2 provides an additional delay of 0.1 second. Closing
both SW3-1 and SW3-2 provides an additional delay of 0.3 second. Section 2 illustrates the location of
SW3.
The instantaneous element in BE1-50/51B-231 relays may be set lower than the instantaneous element
in ABB relays and still have the same reach. This is because the BE1-50/51B-231 instantaneous element
effectively eliminates the fault current transient overreach components. When calculating BE1-50/51B-
231 relay instantaneous element settings, calculate the symmetrical value without any adder for transient
overreach.
Figure 1-2. Instantaneous Characteristic Curves
P0048-10