Siemens JFR Distribution Step Voltage Regulator 21-115532-001 - Manual (Page 9)

INTRODUCTION
Page 5
PROTECTIVE MEASURES
Bypass Arrester. All JFR regulators are equipped with a
properly sized arrester, connected externally between the 'S'
and 'L' line terminals. The arrester is provided to protect the
series winding of the regulator from line surges. By itself, the
bypass arrester does not provide lightning protection for the
regulator.
Lightning Protection. The number of lightning arresters used
will be a discretionary decision on the part of the user,
considering such factors as isokeraunic level and degree of
risk of damage to be accepted. The minimum recommended
lightning protection consists of a properly sized arrester
between the 'S' or 'L' bushing and ground on a single phase
or a wye connected system. A delta connection system
requires the use of two arresters to accomplish minimum
protection levels. Additional protection can be obtained with
the use of arresters at both the 'S' and 'L' terminals in single
phase or wye systems and on all three terminals on a delta
system.
For best results, install lightning arresters on the mounting
lugs adjacent to the bushings near the top of the tank. The
lugs are 0.5 - 13NC located on 2.5 inch centers. Ground the
arrester(s) and the regulator tank solidly to the same ground
connection. Be careful to keep the ground lead connections
as short as possible.
Thru Fault. Type JFR regulators are rated under condition of
thru-faults per ANSI C57.15.
The user is advised to provide for additional source imped-
ance, bus sectionalizing or other means of limiting the avail-
able thru-fault current if these criteria are exceeded at the
installation.
CONTROL CONNECTIONS
Many regulators can be used at several different nominal
system voltages. It is therefore necessary to assure that the
regulator is properly connected at the 19 pin upper terminal
block for the system voltage on which the particular regulator
will be used.
Figure 5A
For this purpose, it is necessary to use the nameplate
drawing and control diagram found in the control enclosure.
1. Refer to the Nameplate. The P2 column indicates the
correct connection for lead P2 based on the system
voltage. Using the applicable control diagram, the
terminal designation of the nameplate can be cross
referenced to the proper terminal on the 19-pin terminal
block.
2. Depending on the regulator, there may be a second
nameplate column indicating that lead U2 should also be
connected. If so, the U2 column indicates the correct
connection for lead U2 based on the system voltage
Using the applicable control diagram, the “U” terminal
designation of the nameplate can be cross referenced to
the proper terminal on the 19-pin terminal block.
3. For regulator equipped with fans for forced-air cooling,
another set of connections will be shown.
NOTE
Matters specifically relating to the Accu/Stat TM
control used in conjunction with the regulator are
not included in this manual. Refer to the
appropriate control instruction manual.