GENERAL INFORMATION
The FireRight jr II is a precision electronic heating capacity controller. The unit is specially designed for use with ceramic kilns.
The controller regulates the kiln's heating system using a method called "time proportioning". In this method, the heaters are repetitively switched on and off every 30-seconds, which is called the "cycle time". The heating rate is regulated by varying the "on" time during each 30-second cycle. This is called the "duty-cycle", and is usually expressed as a "%" of the cycle time.
For example, to set the kiln at "medium" heat, the FireRight jr II can be manually set to provide a 50% duty cycle. The kiln's heaters will then be switched on for the first 15-seconds of each 30-second cycle. Although the heat is actually produced as a series of pulses, the long thermal time constant of the kiln dampens the system, making it appear as if the heat is being provided by a constant, infinitely variable source.
In the "RUN" mode, the FireRight jr II controls the
heat-up rate by automatically increasing the length of the "on" time during
each successive on-off cycle. The heat-up rate is adjusted y means of a "TURN-UP
TIME" dial, which has a range of zero to 10-hours. A "SET" position on
this same dial provides a means of manually adjusting or presetting the kiln's heating
rate, which is conveniently indicated in "%" on a "bar-graph" type
LED display. When operated in the "HOLD" mode, the controller will maintain
the heating duty cycle at the selected setting indefinitely. The bar-graph provides a
flashing warning when the control is in the HOLD mode.
INSTALLATION
The FireRight jr II can be provided either as a panel suitable for flush mounting, or as a complete self-contained surface mounting controller. The flush mounting unit is usually installed on the kiln, and wired directly to a heating relay inside the kiln's switch box. These units can be used with either 110vac or 220vac power, and are often provided on new kilns as a factory-installed option. The surface mounting unit contains its own heating relay, and is often mounted on the kiln room wall, instead of on the kiln. These units are designed for 208-240vac 50/60Hz single phase power, and will handle up to 48-amps. Please note that the operating temperature for either of these units must not exceed 50C (131F).
Flush mounting panels may be connected for either 110/120v or 208/240v.
If using the panel mounting unit, hook it up according to
diagram "C", then jumper terminals x1 and x2 according to either diagram
"A" or "B". Surface mounting controllers are wired for 208/240vac
only; make the line and kiln connections as shown in diagram "D".
The FireRight jr II's on-off switching action will interfere with
the operation of any motor-driven shut-off timer connected on the load side of the unit,
since the timer will not run during the "off" periods. If it is not convenient
to connect the heating relay downstream from the timer, it is possible to compensate for
this error as noted below.
OPERATION
To operate the FireRight jr II Heating Capacity Controller,
proceed as follows:
If desired, the kiln may be manually adjusted to any heating level, and left at that
level indefinitely (e.g., to "smoke out" sensible moisture prior to starting
the firing). To do this:
To compensate a motor-driven shut-off timer for the error produced by the on/off time-proportioning action, consider the following:
SERVICE
Please refer questions to the kiln dealer or manufacturer from whom the control was purchased.
FireRight Controls warrants FireRight jr II units for
one-year from the date of purchase. Units which develop defects attributable to material
or workmanship will be repaired or replaced without charge. Beyond the warranty period,
factory service is available a reasonable flat rates, and can be handled through your
dealer, or factory-direct