requirements must be coordinated to specific motor.
Delete this paragraph when reduced voltage starters
are not required.
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[Autotransformers shall be rated for medium duty and have taps according to
NEMA ICS 2. For thermal over load protection, the autotransformer shall
have normally closed thermostat wired in series with the normally closed
thermal overload contact of the starter. Initial connection shall be to
the [65] [_____] percent tap.] [Solid State soft-start starters shall be
three phase SCR controlled for stepless reduced voltage starting of
regulate torque during start up and to prevent overload conditions while
motor is running. Starter shall have starting current of 300 percent of
full load amps for thirty seconds, bypass/isolation contactor, and three
phase thermal overload relay.]
2.6.3.3
Auxiliary Contacts
Each controller shall be provided with a minimum of three auxiliary
contacts which can be easily changed from normally open to normally closed.
Where indicated on the drawings, a fourth auxiliary contact and red and
green indicating lights shall be provided.
2.6.3.4
Overload Relays
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NOTE: The standard NEMA Class 20 overload relay
operates at 600 percent of its rating after a
maximum of 20 seconds. Other standards are Class 10
and Class 30, operating at a maximum of 10 and 30
seconds. This may be required for special
applications.
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Except as otherwise indicated, each controller shall be provided three NEMA
Class 20 thermal overload relays with external manual reset. Prior to
shipment of the control centers, the Contracting Officer will furnish the
ratings of the heater elements to be installed in the relays by the
Contractor.
2.6.3.5
[Individual Control Transformers
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NOTE: Delete this paragraph as well as requirement
in a unit compartment or external control source is
provided.
are given as an option. For less than 50 VA, they
are not required or desired. Please refer to NFPA
70 section 430-72(c).
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Where 120 volt ac control of contactors is indicated or required,
SECTION 16403A
Page 24