Specifications

WATLOW IND. WATROD Duct Heater Installation & Maintenance Manual
I&M NUMBER: 316-42-6-1 Page: 2
Date:6/11/2008 Rev: 3.00
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WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE [phone] n FAX [phone]
If solid state power control devices are used, the soft start mode is recommended if available. The
WATLOW Power Series controller offers soft start and heater bakeout operating modes to assure the
safest possible startup of heaters that have absorbed moisture. All solid state power control devices
must be protected with fuses designed to prevent damage to the device in the event of a short circuit.
For SCR protection I2t fusing is required and must be sized below the I2t rating of the SCR to insure
protection. If a fuse opens during operation, contact the factory to discuss why the fuse blew, and
determine what the necessary corrective action is.
2. Dielectric strength (HiPot)
The dielectric strength was tested to the applicable standard(s) at the Watlow manufacturing facility prior
to shipement. To assure that the product was not subjected to any conditions that may have decreased
the dielectric strength below desired levels during shipment, etc. a 1000 VAC HiPot test is suggested.
Higher dielectric test values should be reviewed by Watlow prior to testing. It is recommended to
perform the HiPot test prior to connection of the voltage supply to avoid upstream damage to other
components. Follow the HiPot testing procedures issued by the equipment manufacturer.
3. Protection of heater elements from over temperature
The use of temperature controls to regulate heating process and prevent heater over temperature is
highly recommended to ensure safe heater operation. It is the users responsibility to ensure safety of
the installation.
WARNING: Install high temperature control protection in systems where an over temperature
fault condition could present a fire hazard or other hazard. Failure to install temperature control
protection where a potential hazard exists could result in damage to equipment and property,
and injury to personnel.
Failure of components in a temperature control loop, such as the sensor, heater control relay or main
temperature control, can result in damage to a product in process, a melt down of a heater, and / or
damaging fire.
To protect against this possibility, over temperature protection must be provided to interrupt or remove
power from the heater circuit. A bulb and capillary thermostat is not recommended for this function
since it may not respond quickly enough to adequately protect the heater. In cases where the
thermostat bulb gets too hot before the system is turned off, the thermostat bulb could rupture.
This could result in the thermostat remaining in the "ON" condition since there is insufficient
fluid to move contacts apart. We recommend the temperature protection have appropriate third party
approval, and be applied in the classification for which it was tested and approved.
4. Terminal Enclosures
Terminal enclosures should be selected to be compatible with the environment in which the heater will
be located. It is the users responsibility to determine the need for correct rating of the Terminal
enclosure. This should be based on appropriate national and local electrical codes. Failure to use a
compatible enclosure could result in heater damage and personnel danger.
Standard terminal enclosures are designed for general purpose use and are rated general purpose ( ex
NEMA 1). These enclosures should be applied where there will be no danger of spilled liquids,
dampness, dirt, or hazardous gas, fibers or dust. eous conditions. Enclosures for wet or hazardous
locations are also available from Watlow.
Although enclosures are supplied over the terminals, units should be located in an area that will minimize
the chance of being hit by falling or moving objects. The terminals must be protected at all times from
moisture.