ABB DPU 1500R Instruction Book page 93

9/99
51V
4. If a voltage-controlled overcurrent (51V) function is desired,
see the following example. The Boolean Logic OUT2 = 50P-2
(3I>>2) * 27-1P (U<). 50P-2 is a definite time overcurrent
element, and output 2 is connected to the trip bus.
Ground Torque Control
5. In the following example, the ground relay functions (51N & 50N) will be disabled when I2 and I3 are asserted. I2
can be connected to a panel mounted toggle switch for local control, and I 3 can be connected to an RTU for
remote control. When the ground relay is disabled, a message will appear in the MMI display. The Boolean
Logic for the User Display Indication (UDI) is I2 + I3 = UDI. The Boolean Logic for the Ground Enable(GRD) is
NOT I2 * NOT I3 = GRD; and OUT-1 = GRD-D (Ground Disable Alarm). Notice that GRD-D is the NOT of GRD,
so that (by DeMorgan's Theorem) the OUT-2 logic becomes I2 + I3 = GRD-D.
Blown Fuse Alarm
6. In this example, the negative sequence overcurrent
(46) and the undervoltage (27) elements work
together to detect a blown transformer high-side
fuse. The Boolean Logic is OUT-2 (blown fuse) =
46 (Insc>) * 27-1P (U<).
Programmable Input and Output Contacts
Figure 6-9. Ground Relay Control Logic
website:www.abb.com/papd
ABB Distribution Protection Unit 1500R
Figure 6-8. 51V Tripping Logic
Figure 6-10. Blown Fuse Alarm Logic
6-15