3
Electrical Instructions
The potentially high operating and ambient temperatures of
Circulation Heaters require field wiring to the heater to be
carefully matched to the application to avoid serious injury
or damage to the equipment. The wiring must be de-rated
for the expected terminal box temperature.
The size and type of incoming field wiring will depend upon
the heater terminal box temperature, heater current draw
per conductor, number of conductors per conduit, and wire
insulation rating. Refer to the National Electrical Code.
The terminal box temperature is a function of the process
fluid temperature at the terminal box end of the heater. For
liquid systems, the terminal box temperature can be
estimated to be equal to the fluid temperature minus 50
q
F.
For gases, use the temperature of the gas. Extended
terminal boxes are provided on high temperature heaters to
allow moisture seals on the heating elements, and to avoid
costly high temperature wire. Refer to the Application Data
for the INDEECO estimated terminal box temperature.
Field supplied conductors must be sized for at least 125%
of the circuit current.
To calculate the circuit current (in amps):
KW x 1000
Single phase
Line current
Line Voltage
KW x 1000
Three phase
Line current
1.732 x Line Voltage
Wiring to the heater should be permanently installed in
metallic or non-metallic electrical grade conduit in
accordance with all applicable electrical codes, and should
include a grounding conductor if non-metallic conduit is
used.
Field supply wiring must be rated for 600Vac. Use copper
conductors.
The electrical installation should include a service
disconnect switch in sight of the heater as well as branch
circuit over-current protection and over-temperature
protection (if not provided with the heater).
Refer to the wiring diagram included with this instruction
sheet for wiring recommendations. An additional copy is
provided inside the heater terminal box.
Where thermocouple extension wire is required between the
heater and control panel, verify it is connected with proper
polarity as shown on the wiring diagram. Failure to do so
may result in an uncontrolled heater. Refer to the wiring
diagram for the required wire type. Shielded wire is
recommended to reduce signal interference.
Confirm all unused conduit holes in the terminal box are
sealed with plugs suitable for the heater environment.
Attach a ground conductor to the stud located in the heater
terminal box or by other appropriate means per NEC Article
250.
Be sure the terminal box cover is properly installed at all
times to ensure personnel protection. Also, contaminants
can create leakage, (shock) hazards, permanent heater
damage or failure and should be avoided.
It is recommended to perform an insulation resistance test
prior to energizing the equipment. If the value is less than 1
Meg Ohm using a 500Vdc or similar tester, refer to
Maintenance and Troubleshooting sections.
OPERATION
To operate this heater, ensure the tank is completely filled
with fluid, start circulating pump, and energize the main
supply disconnect. Set the controlling device to the desired
temperature.
During initial heating, it is recommended to slowly ramp up
the process set point and inspect the heating system for
problems.
DO NOT
operate heaters at voltages in excess of that
marked on the heater. Excess voltage can shorten heater
life or overload the branch circuit wiring.
DO NOT
operate heaters at sheath temperatures higher
than the recommended maximum. Excess temperatures
can cause premature failure. Generally, sheath materials
are limited to the following maximum temperatures.
WARNING
DO NOT TURN ON HEATING ELEMENTS UNTIL
TANK IS COMPLETELY FULL OF FLUID.
Permanent damage may result if elements are
energized when heater is dry.
WARNING
This heater is designed to operate only up to
the maximum pressure and temperature as
shown on the nameplate.
WARNING
Retighten all electrical connections that may have
loosened during shipment. Failure to do so may result
in damage to the heater or risk of fire.
