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Power Automation and Protection Division
Schematic - - - - - - - - - - - - - - - - - - - - - 1608C93
Component Location Diagram - - - - - - - 1498B40
The Display module contains a blue vacuum fluorescent alphanumeric display, with 4 characters in the function
field and 4 characters in the value field; it also includes 7 LEDs, 7 push-button switches and 5 test points ( See
Figures 1-1, F-1 and Schematic ). The 7 push-button switches (SW1 thru SW7) are used to activate the following
functions on the front panel:
• Display Select (the LEDs, to the right of this push-button, indicate the selected function)
• Reset (the targets selected)
• Function Raise (move to the following function)
• Function Lower (move to the previous function)
• Value Raise (move to the next higher value)
• Value Lower (move to the next lower value)
• Enter (the value that has been selected for upper contact testing)
The Microprocessor module scans these switches once every cycle while in the "background" mode, where it
looks for phase current or phase voltage disturbances. When a phase disturbance is detected, the relay enters
the "fault" mode. While scanning, the Microprocessor module updates the Display module via the ICs (U1, U2,
U3 and U4). The display will be blocked momentarily once every minute due to the self-check function. This is
for readout check and will not interrupt the relay protection function. The Microprocessor also illuminates some
LEDs when the Display Select Switch is depressed. IC (U5) controls the LEDs, which are as follows:
• Relay In Service (DS2)
• Settings (DS3)
• V/I/Angle (DS4)
• Last Fault (DS5)
• Previous Fault (DS6)
• Value Accepted (DS7)
• Test (DS8)
Test points (TP1 thru TP5) are used to monitor dc voltages:
• -24V
• + 5V
• -12V
• +12V
• Common
REL 352 Version 1.00
DISPLAY MODULE
(TP1)
(TP2)
(TP3)
(TP4)
(TP5)
I.L. 40-201.9
A
P
P
E
N
D
I
X
F
F-1
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