Current-sensing transformers (CTs) located inside the
VFI transformer provide line current information to the
electronic control. When line current exceeds the minimum
trip setting, the control initiates a signal which causes the
VFI interrupter mechanism to trip and then interrupt the
circuit. All three phases will open when the VFI interrupter
mechanism is tripped, regardless of whether the trip was
single-phase or three-phase initiated.
Refer to Service Information S285-75-1, Tri-Phase, TPG,
and TPG with SCADA Electronic Control Installation and
Operation Instructions for electronic control operation
instructions.
Standard electrical ratings for Eaton VFI transformers are as
follows:
Continuous Current (max) .....................600 A
Interrupting Current (sym./asym.)...........12 kA/20 kA
Momentary Current 10 cycles (asym.) ............20 kA
1-Second Withstand Current (sym.). .............12 kA
Making Current (sym.) ........................12 kA
For further information on Eaton VFI transformers including
additional ratings, contact your Eaton representative.
Air switches (Arc-Strangler
®
)
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.
16 Three-phase pad-mounted compartmental type installation and maintenance instructions MN202001EN August 2015
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