Figure 4-19. Percentage Differential Screen, 87ND/187ND Tab
Retrieving Neutral Differential Status from the Relay
The status of each logic variable can be determined from the ASCII command interface using the RG-
STAT command or using the BESTCOMS
Metering
screen. See Section 6,
Reporting and Alarm
Functions, General Status Reporting,
for more information.
OVERCURRENT PROTECTION
50T - Instantaneous Overcurrent Protection with Settable Time Delay
There are eight independent function blocks for phase (50TP, 150TP, 250TP, 350TP, 450TP, 550TP,
650TP, 750TP), five for neutral (50TN, 150TN, 250TN, 350TN, 450TN), and four for negative-sequence
(50TQ, 150TQ, 250TQ, 350TQ) instantaneous overcurrent protection. Each function block can be
attached to any of the four hardware CT input circuits or the two virtual current circuits by the BESTlogic
mode setting. See Section 3,
Inputs and Outputs,
for details on the virtual current circuits.
The instantaneous overcurrent protective functions in the BE1-CDS240 relay are labeled 50T because
each has a settable time delay. If the time delay is set to zero, they operate as instantaneous overcurrent
relays.
Figure 4-20 shows the 50TP phase instantaneous over-current as a typical 50T function. Each of the nine
independent functions has two logic outputs: #50TnPU (picked up) and #50TnT (trip) where n indicates
whether it is a P (phase), N (neutral), or Q (negative-sequence) and the #50 differentiates between the
protective functions (50, 150, etc.).
Figure 4-20. Instantaneous Overcurrent Logic Block
9365200990 Rev F
BE1-CDS240 Protection and Control
4-23
Summary of Contents for BE1-CDS240
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Page 349: ...Figure 12 5 Horizontal Rack Mount Front View 9365200990 Rev F BE1 CDS240 Installation 12 5 ...
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