I.L. 40-201.9
Power Automation and Protection Division
1-4
REL 352 Version 1.00
See Appendix G for further details
1.8
Analog Input Module
This module (
see Appendix H
) interfaces with the voltage and current transformers that are
mounted on the Backplane module. These transformers provide the following ac values: V
A
,
V
B
, V
C
, I
A
, I
B
, I
C
. These values are applied to active third-order Butterworth antialiasing filters,
with a cut-off frequency determined by the Nyquist criterion and the system sampling rate. Val-
ues I
A
, I
B
, I
C
are summed to produce 3I
0
.
All 7 inputs (V
A
, V
B
, V
C
, I
A
, I
B
, I
C
, 3I
0
) are connected to the multiplexer and to the A/D converter.
The A/D converter is a self-calibrating 12-bit (plus sign), with an internal track-and-hold ampli-
fier. Additionally, the autoranging circuitry provides 16 bits of dynamic range needed to mea-
sure high fault current values.
1.9
Contact Outputs
• 4 make contacts (2 trip, 2 BFI); 8 additional optional contacts when Extended Contact Output
option is used
• Reclose initiate (2 Form A)
• Reclose initiate (2 Form A)
• Reclose block (2 Form A)
• General start (1 Form A)
• System failure alarm (1 Form B)
• Trip alarm (2 Form A)
• Channel alarm (1 Form A)
2.
SELF-CHECKING SOFTWARE
REL 352 continually monitors its ac input subsystems using multiple A/D converter calibration-
check inputs, plus loss-of-potential and loss-of-current monitoring. Failures of the converter, or
any problem in a single ac channel which unbalances nonfault inputs, trigger alarms. Self-
checking software includes the following functions:
a.
Digital Front-end A/D Converter Check
b. Program Memory Check Sum
Immediately upon power-up, the relay does a complete ROM (EPROM) checksum of program
memory. Afterwards, the REL 352 relay continually computes the program memory checksum.
System
Voltage
Circuitry Supplied
System
Voltage
Circuitry Supplied
System
Voltage
Circuitry Supplied
8.5 Vdc
Processor Board
+5 Vdc Supply
-12 Vdc
Analog circuitry
-24 Vdc
Channel Modem
VF Display COPS
Chips
+12 Vdc
Analog Circuitry
+24 Vdc
Channel Modem,
PONI Module
6.5 Vac
Vacuum Fluorescent
Display Filament