Basler BE1-CDS220, Instruction Manual

Page: 51 / 476

BE1-CDS220 Input And Output Functions 3-3
Nominal Frequency. When the current is too low for the frequency to be reliably measured, the ADC
circuit defaults to operation at the nominal frequency setting. This can be set for operation on either 50 or
60-hertz power systems using BESTCOMS, the optional HMI using screen 6.3.2, SETUP\PWR_S\FREQ,
and from the ASCII command interface using the SG-FREQ (settings general-frequency) command.
Normal Phase Sequence. The normal phase sequence setting can be entered using BESTCOMS, the
optional HMI using screen 6.3.3, SETUP\PWR_S\P_SEQ, and from the ASCII command interface using
the SG-PHROT (settings General-Phase Rotation Sequence) command.
Current Input Circuit Settings. The BE1-CDS220 relay requires information on the CT connections and
the characteristics of the protected zone. For each three-phase CT input circuit, it is necessary to enter
CT ratio, CT connection, transformer connection (if applicable), and optionally whether there is a ground
source that must be taken into consideration.
Each set of three-phase CTs can be connected in wye or one of two delta configurations as shown in
Figure 3-2. As described in Section 1, General Information, Differential Protection Application
Considerations, wye CT connections are recommended for most applications. The CT ratio should always
be entered as the actual ratio and not the effective ratio. When the CTs are connected in delta, the
secondary current under balanced conditions is increased by a factor of the square root of three, yielding
an effective ratio that is lower than the actual CT ratio. The BE1-CDS220 automatically considers this
factor so it is not necessary for the user to manually compensate when entering the CT ratio.
C
B
A
D2837-15
12-22-98
ZONE OF
PROTECTION
POLARITY
INTO ZONE
WYE DAB DAC
I
B
I
A
N I
C
I
A
-I
B
I
B
-I
C
I
C
-I
A
I
A
-I
C
I
B
-I
A
I
C
-I
B
Figure 3-2. CT Connections
As described in Section 1, General Information, Differential Protection Application Considerations, when
the zone of protection includes a transformer, it may be necessary to provide phase angle and zero-
sequence compensation to the currents used by the differential protection elements (see Sidebar 3-1).
For each CT input circuit, a setting is provided to enter the transformer connection associated with that
input. If there is no transformer within the protected zone, this setting should be set to N/A (Not
Applicable).