GE 489 - Manual (Page 171)

GE Multilin 489 Generator Management Relay 6-9
6 COMMUNICATIONS 6.3 MODBUS MEMORY MAP
6
6.3.4 WAVEFORM CAPTURE
The 489 stores up to 64 cycles of A/D samples in a waveform capture buffer each time a trip occurs. The waveform capture
buffer is time and date stamped and may therefore be correlated to a trip in the event record. To access the waveform cap-
ture memory, select the channel of interest by writing the number to the Waveform Capture Channel Selector (30F5h).
Then read the waveform capture data from address 3100h-31BFh, and read the date, time and line frequency from
addresses 30F0h-30F4h.
Each communications port can individually select a Waveform Channel Selector of interest by writing address 30F5h. This
way the front port, rear port and auxiliary port can read different Waveform Channels simultaneously.
The channel selector must be one of the following values:
6.3.5 DUAL SETPOINTS
Each communications port can individually select an Edit Setpoint Group of interest by writing address 1342h. This way the
front port, rear port and auxiliary port can read and alter different setpoints simultaneously.
6.3.6 PASSCODE OPERATION
Each communications port can individually set the Passcode Access by writing address 88h with the correct Passcode.
This way the front port, rear port and auxiliary port have individual access to the setpoints. Reading address 0203h, COM-
MUNICATIONS SETPOINT ACCESS register, provides the user with the current state of access for the given port. A value
of 1 read from this register indicates that the user has full access rights to changing setpoints from the given port.
VALUE SELECTED A/D SAMPLES SCALE FACTOR
0 Phase A line current 500 counts equals 1 × CT primary
1 Phase B line current 500 counts equals 1 × CT primary
2 Phase C line current 500 counts equals 1 × CT primary
3 Neutral-End phase A current 500 counts equals 1 × CT primary
4 Neutral-End phase B current 500 counts equals 1 × CT primary
5 Neutral-End phase C current 500 counts equals 1 × CT primary
6 Ground current 500 counts equals 1 × CT primary or 1A for 50:0.025
7 Phase A to neutral voltage 2500 counts equals 120 secondary volts
8 Phase B to neutral voltage 2500 counts equals 120 secondary volts
9 Phase C to neutral voltage 2500 counts equals 120 secondary volts