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Figure 2: Cable Lead-in Assembly
Rating
Each device has output voltages of 115 and 66.4 for the
main burden (terminals S1, S2, S3) and an auxiliary winding
provides the same voltages (terminals Z1, Z2, Z3) for use
when broken-delta connections are required.
The burden ratings of the standard devices, when used with
standard bushings in each case, are shown in Table 1.
Table 1
System
System
Voltage
Voltage
Line-To-Line Line-To-Ground
115 kV
66.4 kV
138 kV
79.7 kV
161 kV
93.0 kV
230 kV
133 kV
287 kV
166 kV
330-345 kV
191-199 kV
* In no case shall the burden on the auxiliary winding (Z1, Z2, Z3) exceed 75 watts.
** Styles do not include lead-in cable, see Table 2.
*** These designs are for ABB or Westinghouse bushings. Bushings by
other vendors require special PBA configuration.
Table 2. Cables with Type A Connectors
Cable Length*
96"
120"
144"
168"
192"
216"
240"
*Cable lengths other than those listed can be ordered if necessary
4
PBA CABLE DRAW NUT
"
Max. Watts*
Device
Total
Style**
Burden
***
25
3D69822G01
35
3D69822G01
45
3D69822G02
80
.....................
100
.....................
150
.....................
Style#
3D69768G01
3D69768G02
3D69768G03
3D69768G04
3D69768G05
3D69768G06
3D69768G07
Since the device rating is a function both of the system
voltage and of the particular bushing capacitance values, it
is obvious that special bushings, or standard bushings
used at non-standard voltages may have burden ratings
which are at variance with the foregoing tabulation. In this
connection it is to be noted that the auxiliary capacitance
built into each device varies according to the device
application. See page 10 "Calculation of Approximate
Adjustment."
Performance
The Type PBA2 Potential Device is a Class""A" device as
defined by AIEE Standard # 31 and NEMA Standards
SG4-1968. The regulation characteristics with respect to
varying line voltage and varying burden meet the limits
established by these standards.
Since this type of device is basically a series-tuned
device it is sensitive to the system frequency. For small
frequency deviations there is practically no ratio effect,
but there is a slight phase shift. For example, a deviation
of one hertz in 60 will produce a phase shift up to 2
degrees, depending on the particular bushing device and
system voltage. The greatest phase shift is experienced
when the potential device is loaded to its rating, and when
the normal system voltage is low relative to the bushing
rating.
When high-speed directional relays are energized from
this device, it is recommended that the basic burden be
power factor corrected to 100%, or slightly leading, and
that the device be loaded to its rating in watts (as shown
on the nameplate), by adding parallel resistance if
necessary. The purpose of this is to reduce to a minimum
the possibility of incorrect relay operation, which might
result from device output transients following a system
short circuit extremely close to a device.
PBA CONNECTION
HOUSING
"
ABB
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