Installation (continued) – Howard SVR1 Regulator User Manual

Page 7

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SVR-1 Step Voltage Regulator

Document No. 2.4.114

Revision: 03

Issued: March, 2012


Copyright © 2012 Howard Industries, Inc.

INSTAllATION (Continued)


SVR-1 regulators can be used on several different system

voltages. A cover-mounted terminal block (Figure 3) is

provided, so that control and fan leads (if present) can be

connected as necessary to accommodate the particular

system voltage to be regulated.

SVR-1 regulators may be operated at less than the rated

voltage as indicated on the nameplate. When operated at

less than rated voltage, regulator kVA is reduced, except

when operating a 7.62kV regulator at 7.2kV.

In order to properly connect the control leads, it is

necessary to refer to the control diagram found on the

nameplate (Figure 2). The control diagram will aid in the

identification of the appropriate terminal connections.

Follow the instructions listed below:

1. Referring to the regulator nameplate diagram,

connect the “PS” lead as indicated for the applicable

system voltage.

2. For some regulators the nameplate will indicate a

connection for the “MS” lead. Connect this lead as


3. For regulators equipped with cooling fans,

connect fan leads as indicated.


Each SVR-1 regulator is equipped with an appropriately

sized by-pass surge arrester connected between the

“S” and “L” high-voltage bushing terminals. This by-pass

arrester (sometimes refered to as the “series arrester”)

is provided to protect the series winding of the regulator

from damage due to line surges. The by-pass arrester

does not provide complete lightning protection for the

regulator. Improved lightning protection can be provided

as described below. Refer to the connection diagrams on

page 9.


Lightning protection can be provided by adding appropri-

ately sized surge arresters to the “S” and “L” bushing ter-

minals. These arresters (called “shunt arresters”) should

be mounted on the regulator tank adjacent to both the

“S” and “L” bushings using the supplied mounting provi-

sions. The top lead of each arrester should be connected

to the adjacent bushing terminal. Arrester grounding is

achieved through the arrester mounting brackets. Refer

to the connection diagrams on page 9.


SVR-1 regulators are designed to withstand through-fault

currents of 25 times the nameplate rated ONAN current

as described in IEEE Standard C57.15-2009.

In order to limit through-fault current to acceptable levels

as described above, the user should consider the applica-

tion of additional source impedance, bus sectionalizing,

or other methods.


Regulators can be modified at factory for 50 Hertz

operation with appropriate derating of voltage. Contact

the Howard Industries Regulator Division for information

about regulators specifically designed for 50 Hertz.