Eaton EVER-Tap, Installation, Operation And Maintenance Instructions

Page: 17 / 52

Position indicator and ADD-AMP capability
Regulators rated below 668 A include an ADD-AMP
feature which permits additional current-carrying capacity
at reduced voltage regulation range, as shown in Table 2 ,
but not to exceed 668 A. The ADD-AMP type adjustment
is located inside the position-indicator faceplate to prevent
inadvertent adjustment. In addition, a Soft ADD-AMP control
feature allows adjustment by way of the keypad or interface
software. An optional ADD-AMP feature maximum of 875 A
is provided when specified for regulators rated 438–668 A.
Table 2 . ADD-AMP adjustments
Regulation (%) Current (%)
± 10.0 100
± 8.75 110
± 7.5 120
± 6.25 135
± 5.0 160
The position indicator (see Figure 2 and Figure 13 ) is
mounted on the junction box on the cover of the regulator
and is directly connected to the tap-changer by a flexible
drive shaft passing through the junction box and terminal
board via a sealing gland.
The indicator face is graduated in steps. Drag hands indicate
the maximum and minimum positions attained during raise
and lower operations. The drag hands are reset around the
main hand position by operating the drag-hand reset switch
on the control front panel.
During forward power flow, the main hand of the position
indicator will be to the right of the neutral position when the
regulator is boosting. During reverse power flow, the main
hand will be to the left of the neutral position when the
regulator is boosting.
The limit switches on the position indicator can be adjusted
to limit the maximum and minimum tap positions with
possible settings of raise or lower 8, 10, 12, 14 or 16.
These limits correspond to percent regulation levels of 5,
6 1/4, 7 1/2, 8 3/4, and 10%. The five possible load current
ratings associated with the reduced regulation ranges
are summarized in Table 11 (page 38) and Table 12
(page 39). Higher regulation ranges are realized in closed
delta application.
When using the limit switches, a detent stop at each
setting provides positive adjustment. Settings other than
those stops are not recommended. The raise and lower
limits need not be the same value unless reverse power is
possible. The regulator will stay within the ADD-AMP limits
set forth by the control or the position indicator, whichever
limit is of a lower regulation percentage.
otee: N If Soft ADD-AMP limits have been programmed into
the control and the position indicator limit switches
have not been set, it is possible to manually step
the tap-changer beyond these limits. If the unit is
switched back to automatic mode, the control will
step the regulator back to within the Soft ADD-AMP
limits set in the control.
Surge protection
Series arrester
All Eaton voltage regulators are equipped with a bypass
arrester connected across the series winding between the
source (S) and load (L) bushings. This arrester limits the
voltage developed across the series winding during lightning
strikes, switching surges, and line faults. The series surge
arrester can be seen in Figure 2 . A heavy-duty MOV-type
series surge arrester of 3 kV offers series winding
protection on all regulators except those rated 22,000 V and
greater, which have a 6 kV MOV-type series surge arrester.
Shunt arresters
A shunt arrester is a recommended accessory on Eaton
voltage regulators for protection of the shunt winding. The
shunt arrester is a direct-connected arrester mounted on
the tank and connected between the bushing and ground
(earth). It is recommended that arresters be applied to all
non-grounded bushings.
For best results, locate these arresters on the mounting
pads provided on the tank near the bushing. Connect
the arrester and the regulator tank to the same ground
connection using the shortest cable possible. Shunt arrester
application data is listed in
Table 3
.
Table 3 . Typical shunt arrester application data
a
Regulator
Voltage
Rating
Recommended
MOV Shunt
Arrester
Ratings (kV)
Regulator
Voltage
Rating
Recommended
MOV Shunt
Arrester
Ratings (kV)
2500 3 14400 18
5000 6 15000 21
6600 9 19920 27
7620 10 22000 27
8660 12 33000 36
11000 15 34500 36
13800 18
a
Contact factory for specific shunt arrestor application ratings.
13
VR-32 and EVER-Tap™ Voltage Regulator
InstallatIon, operatIon, and MaIntenance InstructIons
MN225008EN June 2020