Internal loadbreak switches
It is recommended that remote energization be used
whenever possible. Operate loadbreak switches using
hotstick tool. After loadbreak switch is switched to “OPEN”
position, verify that transformer secondary terminals have
zero voltage and then ground the secondary terminals to
prevent transformer backfeed energization.
Two-position loadbreak switch
The operating mechanism of the Eaton’s Cooper Power
series two-position loadbreak switch employs a manually-
charged over-toggle stored spring assembly which
performs independent of operator speed. The spring-loaded
activating mechanism ensures quick loadbreak or loadmake
operations in less than one cycle. Incorporated into the
switch mechanism are internal stops that restrict the handle
orientation to only two positions: “OPEN” and “CLOSED”
(see Figure 16). The switch should be hotstick-operated and
will require 15 ft-lbs. minimum input torque to operate.
Refer to
Catalog Section CA800019EN Two-Position Sidewall
(Horizontal) and Cover (Vertical) Mounted Loadbreak
Switches
for two-position loadbreak switch ratings.
External visible loadbreak switch
The Eaton’s Cooper Power series external visible loadbreak
switch is a great way to verify isolation of internal transformer
circuitry. Having visual confirmation that the secondary
bushings are de-energized saves both time and money,
while providing an added safety feature. It is strongly
recommended that if breaking load with this switch, the
viewing window be fully covered and locked into place.
Viewing this switch during operation under load could be
dangerous to the human eye. The external visible loadbreak
switch is always shipped with a padlockable cover box. It is
also important to remember that even after breaking load, the
incoming high voltage cables are still live and dangerous.
Figure 16. Two-position loadbreak switch handle and
indicator plate.
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment.
• Do not operate loadbreak equipment if a fault
condition is suspected. Doing so can cause an
explosion or fire.
• Use a hotstick to operate transformer loadbreak
equipment.
• After operating transformer loadbreak equipment,
check that voltages at transformer terminals are
the expected values. Checking voltages verifies that
loadbreak equipment operated properly and that
electrical circuit conditions are as expected.
• Before servicing transformer secondary connected
equipment, verify that all transformer secondary
terminals have zero voltage and ground the
transformer secondary terminals following industry
accepted safe grounding practices. Grounding
secondary terminals protects against situations such
as a standby generator energizing transformer from
the secondary circuit.
• Before servicing transformer, ALWAYS de-energize
the transformer from a remote upstream source and
then proceed to ground all primary and secondary
transformer terminals following industry accepted safe
grounding practices. Grounding secondary terminals
protects against situations such as a standby
generator energizing transformer from the secondary
circuit.
• Follow industry accepted safety practices. Utilize
protective clothing and equipment when working
with loadbreak equipment.
WARNING
Three-phase pad-mounted transformers use
conventional transformer oil, R-Temp fluid, or
Envirotemp™ FR3™ fluid for an insulating liquid. When
the insulating liquid temperature is less than -20 °C
(-4 °F) for conventional transformer oil, less than 0 °C
(32 °F) for R-Temp fluid or less than -10 °C (14 °F) for
Envirotemp™ FR3™ fluid, viscosity is reduced, which
may reduce make and break capabilities of loadbreak
devices. Below these temperatures, under-oil loadbreak
accessories should not be used to make or break a
load. Instead, de-energize transformer from a remote
upstream source before operating under-oil loadbreak
devices.
CAUTION
Always fully cover and lock external visible loadbreak
switch window during operation. Failure to cover and
lock this window could cause personal injury. Before
operating the on/off/ground switch, it is important to
ensure the transformer tank has been fully grounded.
Always check fluid temperature before operating
loadbreak devices.
11
Three-phase pad-mounted compartmental type installation and maintenance instructions
MN202001EN August 2015
