VICI ITC - Manual (Page 4)

1.12 Proportional Heater Power Control
The ITC utilizes proportional power application to minimize temperature overshoot,
and improve temperature stability about the setpoint. Controls are accessible to
the user, allowing the proportioning bandwidth (in
o
C) to be adjusted to meet
specific requirements.
1.13 Power Attenuation
Many temperature controllers are used in conjunction with variacs (variable output
transformers) in order to improve temperature stability. By reducing the maximum
power available to the heater, the user is adjusting the heater "size" to suit his
particular thermal system. This is a practical, flexible solution to the problem, but
requires two devices to control the temperature, one of which is heavy, inefficient,
and expensive.
The ITC employs a pushbutton switch so the user can attenuate the total power
available to the heater circuit. Attenuation is selectable from 0 to 90%, in incre-
ments of 10%.
1.14 Zero Crossing Power Application
Power is applied to the load in increments of integral half cycles, only. This
technique drastically reduces RFI/EMI normally associated with high current AC
switching.
1.15 Digital Temperature Setting
The ITC employs a bank of three digital thumbwheel switches for temperature
setpoint selection. The setpoint is selectable in 1
o
increments. The most obvious
advantage to this scheme is 100% setting repeatability.
1.16 Compact Rugged Construction and Functional Layout
The ITC’s physical characteristics are strictly utilitarian. In all cases, rugged
construction techniques are employed, insuring that the assembled instrument is
not delivered by a freight company in kit form. The instrument is housed in an
aluminum/cycolac enclosure measuring 2.4" x 8.3" x 5.9". The top of the enclo-
sure can be quickly removed, allowing access to all fuses, electronics, etc.
It is worthy of note that almost all electronic components are mounted on a single
printed circuit board. This feature directly translates to simple troubleshooting
methods and minimal spare parts inventory.
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