GE 489 Communications Guide

489 GENERATOR MANAGEMENT RELAY – COMMUNICATIONS GUIDE 71
Table Notes:
1. Unless otherwise specified, an event object will be generated for a point if the current
value of the point changes by an amount greater than or equal to two percent of its
previous value.
2. An event object is created for the Frequency point if the frequency changes by 0.04 Hz
or more from its previous value.
3. An event object is created for these points if the current value of a point is in any way
changed from its previous value.
4. To support existing SCADA hardware that is not capable of 32-bit data reads, the
upper and lower 16-bit portions of these 32-bit values have been assigned to
separate points. To read this data, it is necessary to read both the upper and lower 16-
bit portions, concatenate these two values to form a 32-bit value and interpret the
result in the format associated with the point as specified in Data Formats on page
CG–42.
5. The data returned by a read of the User Map Value points is determined by the values
programmed into the corresponding User Map Address registers (which are only
accessible via Modbus). Refer to User-Definable Memory Map Area on page CG–11 for
more information. Changes in User Map Value points never generate event objects.
Note that it is possible to refer to a 32-bit quantity in a user map register, which may
require the use of a 32-bit variation to read the associated analog input point.
6. The scale for pre-trip currents is determined by the value in point 9, which should not
normally change
7. The scale for currents is determined by the value in point 47, which should not
normally change
8. Each power quantity is available at two different points, with two different scale
factors (kW and MW, for example). The user should select the unit which is closest to
providing the resolution and range desired. If 32-bit analog input capability is present,
the higher-resolution (kW, kvar, kVA) points should generally be used, since they
provide the greatest resolution.
246 - User Map Value 124 Note 5
247 - User Map Value 125 Note 5
248 F118 Active Setpoint Group Class 1 Note 3
249 F13 Positive kWh Class 2
250 F13 Positive kvarh Class 2
251 F13 Negative kvarh Class 2
252 F12 Generator Hours Online Class 2
Table CG–8: Analog Inputs Point List (Sheet 5 of 5)
INDEX FORMAT DESCRIPTION EVENT CLASS
ASSIGNED TO
NOTES

GE 489 Specifications

General

Brand	GE
Model	489
Category	Relays
Language	English