individual control transformer shall be provided on the line side of the
unit disconnect. The control transformers shall be rated 480-120 volts and
shall conform to the requirements for control transformers in NEMA ST 1.
Control transformers shall have adequate volt-ampere capacity for the
control functions indicated. Transformers shall be installed [without]
[with] primary fuses. [Primary fuses shall be Class J.] Except as
otherwise indicated on the drawings, each control transformer shall be
provided with a fuse in one secondary lead and shall have the other
secondary lead grounded.]
2.6.3.6
[Voltage Fault Protection
**************************************************************************
NOTE: Voltage fault protection requirements should
be evaluated and this paragraph deleted when not
required.
**************************************************************************
Where shown, starters shall be provided with protection against [voltage
faults,] [phase unbalance,] [phase loss,] [phase reversal,] [undervoltage]
[and overvoltage]. Upon sensing one of these faults, the protector shall
de-energize the starter. The protector shall use a combination of voltage
and phase-angle sensing to detect phase loss even when regenerated voltages
are present. The protector shall be connected to the load side of the
motor circuit disconnect. The protector shall have an adjustable line
voltage trip level, adjustable trip delay, automatic reset [and manual
reset by an external normally closed push-button,] and Double Pull Double
Throw (DPDT) output contacts. Protector operation shall have repeatability
of +1 percent of set point, maximum, and a dead band of 2 percent maximum.
Protector shall have green indicator to show normal status and red
indicator to show tripped status. Indicators will be visible through the
compartment door, when LED's are used protector shall be covered with a
clear unbreakable cover, when lamps are used they shall have nameplates and
be grouped with other indicating lights.]
2.6.3.7
Control Circuit Disconnects
**************************************************************************
NOTE: The requirement for disconnect of the control
circuit when the unit compartment is open complies
with NFPA 70 Article 430 F section 430-74.
Generally, manufacturers do not disconnect control
voltage except when racking out the starter unit,
meeting California code, but not NFPA as currently
written. With racking, control circuit voltage is
present when the unit compartment is open, which may
be a safety risk. This paragraph is a specialized
requirement to avoid such a safety hazard. Specific
designs may require a variance. There are available
high density pull apart terminals in the unit
compartments to disconnect control voltage, after
the unit is open. The latter meets the intent of
NFPA, but not the letter. The designer shall
investigate specific project requirements for
interlocking and safety, and modify this paragraph
accordingly.
**************************************************************************
Control circuit power shall disconnect when the unit compartment is opened.
SECTION 16403A
Page 25
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