ABB PBA2 Instruction For Installation And Maintenance
Bushing Potential Device,Type PBA2
PTAE-APD903
IZUA 7711-210
Instructions for Installation and Maintenance
All possible contingencies which may arise during installation, operation, or maintenance, and all details and
variations of this equipment do not purport to be covered by these instructions. If further information is desired
by purchaser regarding his particular installation, operation or maintenance of his equipment, the local ABB Inc
representative should be contacted.
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ABB
Description
Application
The condenser bushing potential device is a means for
securing small amounts of 60 hertz power at 115 volts
and 66.4 volts from high voltage lines through the medium
of the condenser bushing. For 115kV and higher voltages
this device is the most economical means of securing
such small amounts of power.
These devices provide a 115 and 66.4 volt output which
is substantially proportional to the system line-to-ground
voltage and in phase with it. This output is commonly
used to energize synchroscopes, voltmeters, and voltage
responsive relays. The device accuracy is not adequate
for use with metering instruments where revenue is involved.
Construction
The potential device is built in an outdoor, weatherproof,
steel housing arranged for mounting on the side of an oil
circuit breaker or transformer in the vicinity of one of the
condenser bushings. A special cable assembly of
weatherproof construction, and with a grounded external
shield, connects the potential device to one of the metallic
layers of the condenser bushing.
The device network (see Fig. 6) consists of a main transformer
having adjustable reactance, an auxiliary transformer of
adjustable ratio, a tapped capacitor to correct burden power
factor, a protective spark gap, and a dead-front adjusting
panel.
A grounding switch permits de-energizing the device, and a
heater (to be energized from an external voltage source)
prevents internal sweating of the housing.
Standardized mounting dimensions permit the interchangeability
with most standard ABB or Westinghouse units sold since
the middle of 1934. The standard device is electrically usable
for most bushings having capacitance taps per IEEE
C57.19.01-2000 Type A: Normally Grounded having the tap
on the second metallic layer above ground potential
includes substan
tured since the middle of 1935 and having a voltage rating of
115kV or higher. Cable lengths (see Fig. 2) are also standard
for circuit breakers, but special lengths are general for transformers. End fittings of cables are common for all.
tially all Westinghouse bushings manufac-
. This
Figure 1: Outline and Mounting
ABB
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PBA CABLE DRAW NUT
"
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 Max. Watts* Device
Voltage Voltage Total Style**
Line-To-Line Line-To-Ground Burden ***
115 kV 66.4 kV 25 3D69822G01
138 kV 79.7 kV 35 3D69822G01
161 kV 93.0 kV 45 3D69822G02
230 kV 133 kV 80 .....................
287 kV 166 kV 100 .....................
330-345 kV 191-199 kV 150 .....................
* 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.
PBA CONNECTION
HOUSING
"
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
ap
plication. 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.
Table 2. Cables with Type A Connectors
Cable Length* Style#
96" 3D69768G01
120" 3D69768G02
144" 3D69768G03
168" 3D69768G04
192" 3D69768G05
216" 3D69768G06
240" 3D69768G07
*Cable lengths other than those listed can be ordered if necessary
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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.
ABB
Erection
The potential device may be lifted from its crate or pallet
and handled by means of the two lifting lugs on the side of
its roof to mount it on the circuit breaker or the transformer.
Depending on the particular breaker or transformer bracket
provided for the lower edge of the potential device, proceed
as follows (see Fig. 1):*
a. If the lower device support on the transformer or breaker
carries two tapped holes then bolt the J bracket, which
is shipped loose with the potential device, to this pad
using the two countersunk head bolts provided. There
is a notch in the center of the rear lower flange of the
device, which will fit into the hook provided by this J
bracket. Rest the weight of the potential device into
this bracket and place the two bolts into the two slots
of the upper device support, and secure these in place.
b. If the transformer or breaker carries a lower device
support consisting of a bent steel bar, and with two
notches cut into its edge instead of two tapped holes,
then the J bracket may be scrapped and the potential
device rested directly on the notched bar. The upper
end is bolted into place with the two bolts.
c. In either case, the paint shall be scraped away from the
upper pad where it is bolted against the corresponding
pad on the breaker or transformer in order to assure a
good ground connection at this point.
d. The primary connection is made by installing the high
voltage cable assembly of Fig. 2. This is done with the
bushing grounded. The cable is installed by
t
he mounting flange cover from the side of the po
device housing and removing the cover from the tap
receptacle on the bushing flange. The tap receptacle
on the bushings of recent manufacture may be found
filled with approximately one pint of transformer oil, which
will drain out when the cover is removed. Discharge the
bushing tap layer by touching the socket
contact with a grounded wire.
removing
tential
1. If the bushing is ABB O plus C or other type that
permits addition of transformer oil to the test tap with
the tap cover in place, you may choose to fill the PBA
connector housing with transformer oil. In this case,
do not add the petrolatum to the PBA connector housing.
2. Otherwise, pack the inside of the PBA connector hous
ing
with the petrolatum provided, taking care to leave no
air pockets.
e. Push the bushing connector into the tap, then thread the
PBA connector housing into the threaded portion of the
bushings tap. Tighten by hand, approximately 1/4 turn
after the gasket is in contact with both the tap and the
connector housing. Lubricate the gasket with a thin
application of transformer oil or petrolatum whichever is
being used.
f. Turn the PBA cable draw nut clockwise, until tight.
g. If you have chosen to fill the PBA connector housing with
transformer oil, do so now. Please see the bushing's
application literature for filling instructions and oil expansions
space requirements.
h. Place the porcelain end of the cable assembly into the
hole in the side of the potential device housing.
Bolt the two flanges in place using the hardware
provided. The composition flange at the cable end
is also the gasket. Draw up the bolts progressively
around the cable so that there is not excessive pressure
at any point. Tighten up the bolts only sufficient to create
a slight bulge all around the edge of the composition.
i. Connect the internal jumper connection in line with
diagram of Fig. 6 by opening the
partially dropping the front panel assem
It is suggested that when a device is installed and con
PBA'S door and
bly.
nected
that its voltage adjustment be set to a minimum (and the
ground switch opened) until such time as the normal burden is connected and the device adjusted.
* If the device is to be mounted on equipment that is not
manufactured by ABB, the mounting arrangement may
be slightly different than described here.
ABB
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