3
III. FIELD INSTALLED CONTROLS
=WARNING=
When making electrical connections to the heater, be sure to follow the
wiring diagram provided with the heater. The heater must not be
operated without the safety high temperature limit cutout properly
connected in the circuit.
1.) All 3 phase heaters and all single phase heaters
above 277 volts or 25 amps rated load current
must have a safety contactor to disconnect the
power if the temperature high limit opens. The
contactor, must be CSA approved for 150,000
cycles with a resistive rating per pole equal to
or greater than the heater rated load current.
The holding coil voltage rating of the contactor
cannot exceed 277 volts.
2.) Any field installed controls cannot exceed the
electrical ratings of the high temperature limit
switch, which is rated for 125 VA at 277 VAC
maximum.
IV. OPERATION
The Explosion-proof Heater may be operated normally
with ambient temperatures of 104°F (40°C) or less,
and in atmospheres containing less than 21% oxygen
by volume. The temperature classification of the
heater must be less than the ignition temperature of
the area hazard classification, and the hazardous
group classification of the heater must match or
exceed the area classification. All of these conditions
must be met before attempting to operate the heater.
The heater should never be operated in an oxygen-
enriched atmosphere or with an ambient temperature
above 104°F (40°C). At high ambient conditions the
safety high temperature limit cutout may activate. If
this occurs, the installation must include some means
to de-energize the heater, such as an automatic
temperature control thermostat or a manually
operated disconnect switch, to prevent excessive
cycling of the controls.
=WARNING=
NEVER operate the heater in an atmosphere with an ignition
temperature lower than the heater marking.
=WARNING=
The heater must be mounted horizontally to maintain the ignition
temperature rating.
1. Initial Operation. Check to make sure the
mechanical and electrical installation is
complete and that it is safe to operate the
heater.
a.) Air Supply. Airflow through the heater
must not be blocked or obstructed in any
manner. Make sure the area below the
heater is clear, and that nothing is laying
on top of or draped over the top of the
heater cabinet.
b.) Close the branch circuit or unit disconnect
switch servicing the heater.
c.) If a control thermostat is used turn the
temperature set point above ambient
temperature.
2.) High temperature limit switch. The high
temperature limit switch is an automatic reset
type. If it trips It will automatically reset once the
temperature has dropped 20°F to 30°F (10°C to
15°C)below its trip point. The automatic reset
high temperature limit control is also a fail safe
device. If the sensing bulb is damaged or broken
the automatic reset temperature limit control
contacts will open and stay open, preventing
heater operation until the control is replaced.
=WARNING=
The heater must not be operated without the safety high temperature limit
cutout properly connected in the circuit.
=WARNING=
Replacement electrical components must be obtained from the factory to
maintain the hazardous location rating.
3.) Normal Operation.
a.) Inspect the heater installation for loose bolts,
covers, signs of overheating or corrosion that
could impair the ability of the heater to operate
safely. Loose bolts should be tightened prior
to operation.
b.) Check the cabinet for restrictions, or
blockages.
c.) Place the heater in service.
V. MAINTENANCE
A. Electrical
=WARNING=
Potentially lethal voltages are present. Be sure to lock the branch
circuit disconnect switch in the off position and tag the circuit “Out for
Maintenance” before working on this equipment.
=WARNING=
Replacement of electrical components should only be done by
authorized personnel familiar with the requirements of maintaining
electrical equipment in an explosion-hazard area.
=WARNING=
Replacement electrical components must be obtained from the
factory to maintain the hazardous location rating.
1.) Annually inspect all wiring connections and visible
insulation for damage, looseness, fraying, etc., as
applicable. Tighten any loose wiring connections
and replace or repair damaged or deteriorated
insulation.
2.) If reduced heat output is suspected verify the
condition of the heating elements by using an
ammeter to check the current draw of each input
line. All input lines should draw approximately
equal current which should agree with calculated
rated load current. If they do not, one or more of
the heating elements could be burned out.
3.) High temperature limit switch. The high
temperature limit switch is an automatic reset
type. If it trips It will automatically reset once the
temperature has dropped 20°F to 30°F (10 to