Ge 489 User Manual download pdf (Page 171)

GE Multilin 489 Generator Management Relay 6-9

6 COMMUNICATIONS 6.3 MODBUS MEMORY MAP

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

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Ge 489 User Manual Page 171