GE 489 Instruction Manual page 106
Generator management relay
Hide thumbs
Also See for 489:
- Instruction manual (314 pages) ,
- Communications manual (78 pages) ,
- Instruction manual (259 pages)
Table of Contents
Advertisement
4.11 S10 MONITORING
The 489 can measure the demand of the generator for several parameters (current, MW, Mvar, MVA). The demand values
of generators may be of interest for energy management programs where processes may be altered or scheduled to
reduce overall demand on a feeder. The generator FLA is calculated as:
Generator FLA
=
Power quantities are programmed as per unit calculated from the rated MVA and rated power factor.
Demand is calculated in the following manner. Every minute, an average magnitude is calculated for current, +MW, +Mvar,
and MVA based on samples taken every 5 seconds. These values are stored in a FIFO (First In, First Out buffer).The size
of the buffer is dictated by the period that is selected for the setpoint. The average value of the buffer contents is calculated
and stored as the new demand value every minute. Demand for real and reactive power is only positive quantities (+MW
and +Mvar).
N
1
∑
Demand
=
--- -
N
n
=
1
where: N = programmed Demand Period in minutes,
n = time in minutes
4
4-68
Generator Rated MVA
--------------------------------------------------------------------------------------------------------------------- -
×
3 Generator Rated Phase-Phase Voltage
Average
N
160
140
120
100
80
60
40
20
0
t=0
t+10
t+20
t+30
Figure 4–21: ROLLING DEMAND (15 MINUTE WINDOW)
489 Generator Management Relay
t+40
t+50
t+60
t+70
t+80
TIME
4 SETPOINT PROGRAMMING
t+90 t+100
GE Power Management
Advertisement
Table of Contents
