Basler BE1-CDS220, Инструкция по эксплуатации

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BE1-CDS220 Metering 5-1
SECTION 5
•
METERING
Metering, as it applies to the BE1-CDS220 relay, is measuring the current inputs, displaying those values
in real time, recording those values every one-quarter second, and calculating other quantities from the
measured inputs. There are two important references. One is that phase angle metering is referenced to
phase A1. (See the following paragraph for more information on phase angle references.) If phase A1 is
not present (zero), all other phase angles will be zero. Two is that the measured frequency is detected by
zero cross-over on phase C1. If phase C1 is not present (zero), all frequency measurements will be NA
(indicates no current flow in the input circuit).
The angles reported by the metering function can be understood by considering the following example. In
response to a request to “Read all metered values when CT circuit is set for a WYE connection”, part of
the report reads “
IA1=4.95A,@ 0;
and
IB1=5.03A,@240;”.
Figure 5-1 shows a polar graph with
counterclockwise rotation. Because phase A current magnitude is 4.95 amperes at an angle of 0 degrees
(it is the reference point), the phasor is on 0 degrees and almost reaches the outside of the circle which is
5.0 amperes. Phase B current is at an angle of 240 degrees and is shown on the polar graph at 240
degrees which is lagging phase A by 120 degrees. Phase B current magnitude is 5.03 amperes and the
phasor extends slightly beyond the circle. All reported angles can be laid out on this polar graph to
indicate leading or lagging quantities.
0°
90°
0°
180°
270°
120°
150°
210°
240° 300°
330°
30°
60°
P0001-19.cdr
07-26-00
IA1=4.95A, @ O°
I
B
1
=
5
.
0
3
A
,
@
2
4
O
°
120° Lagging
Figure 5-1. Polar Graph for Phase Angle Reporting Reference
For information on the current Demand Reporting Functions, see Section 6, Reporting And Alarm
Functions, Demand Functions.
CURRENT METERING
BE1-CDS220 relays provide metering of phases A, B, C, neutral (N), and negative sequence (Q) for CT
circuit 1 and CT circuit 2 as well as the optional independent ground (G). Metering data is available in
primary or secondary current and can be obtained from the HMI screens 3.1 and 3.2, (\METER\CRNT\
and \METER\DIFF\) and their associated sub-screens. This data can also be obtained through the M or
M-I serial communication commands as shown in the following paragraphs. Any individual metered value
may be obtained using these serial commands. BESTCOMS may also be used for metering. For more
information on metering Demand Reporting Functions see Section 6, Reporting and Alarm Functions,
Demand Functions.