number of terminals to connect the heater pigtails and
thermocouples for each hopper zone.
**************************************************************************
NOTE: Use these paragraphs for local control only.
**************************************************************************
b.
Local Hopper Heater Control Panel: Provide each precipitator with
a local hopper heater control panel at each hopper. Locate at a
regularly accessed area near each hopper. For each zone, provide
each local hopper heater control panel with: terminal blocks for
power, control, and alarm circuits, one control temperature
thermostat, one low temperature alarm thermostat, magnetic
contactor and alarm relay with two normally open contacts, and
auxiliary relays for automatic operation of the heater system.
Provide a 3-pole fused switched main disconnect device and a fused
control transformer having a 120-volt AC secondary for each local
hopper heater control panel. Provide thermostats with a set point
range of 38 to 260 degrees C 100 to 500 degrees F. Measure hopper
skin temperature using ungrounded, type J thermocouples. Provide
each local hopper heater control panel cover with the following
devices:
(1)
"START UP," "ON LINE," "OFF," "AUTO" selector switch.
(2) 120 V "ON" red light with integral transformers, one each
zone.
(3) 120 V "LO TEMP" alarm white light with integral transformer,
one each zone.
(4)
Device and enclosure nameplates.
Wire the selector switch for the following system operation:
(1) "START UP":
Upper and lower zones all elements on (includes
throat heater).
(2) "ON LINE":
Single element lower zone on (includes throat
heater).
(3)
"OFF":
All elements off.
(4) "AUTO": Control functions transfer to Master Hopper Heater
Control Panel.
**************************************************************************
NOTE: Use these paragraphs for master control only
**************************************************************************
c.
Master Hopper Heater Control Panel: Provide panels containing
relays, contactors, circuit breakers, control transformers, and
other devices required for complete control of each precipitator
hopper heater system. Locate Master Hopper Heater Control Panels
with precipitator controls in the control room. Factory install
and wire the panel components in a NEMA ICS 6, Type 12 enclosure
and include the following:
(1)
A main circuit breaker.
SECTION 15862N
Page 38
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