Hart 恆溫槽控制儀長久以來一直處於一流水準。這些控制儀是業內流行的改造控制儀，而如今則可用於Rosemount 恆溫槽。7900 型控制儀易於安裝，且能夠替代Rosemount 915 型用於所有型號的Rosemount 恆溫槽。
此控制儀與Hart 的2100 控制儀使用同樣的電路系統，以達到± 0.003 °C 或更優的持久穩定性。特殊的噪音抑制技術使7900 能夠適應此穩定性水平的要求，測量極細微的電阻變化。控制儀內使用交流電橋來消除熱電勢。用戶定制的高精密度電阻器可增強短期和長期穩定性，而先進的過濾技術則會去除擾人的線路噪音。7900 型內置有特殊的迴路，該迴路對控制儀的微處理器實施監控，並在該微處理器操作中斷時自動將其重置。同時，還內置有兩個單獨的斷路器系統，以將槽溫維持在正常範圍之內。
軟件斷路器使用可調整的高溫限制，可通過前控制板方便地進行設定，以配合您的恆溫槽液體的要求。如果控制傳感器測量的溫度超過此上限，則會停止加熱。如果槽溫降至其正常工作範圍以下，則加熱器會起動，而LN 2 冷卻則會關閉。一個次級獨立硬件斷路器利用熱電偶對槽溫實施監控，且會在槽溫升至其範圍以上時，停止所有加熱和LN 2 冷卻。
斷路器的這些功能與7900 的優越可靠性及長期穩定性性能相結合，可以使您隨心所欲地調節系統的連續運行時間—如果您希望，一年連續運行365 天也可以。每天當您步入實驗室時，您的恆溫槽就已準備就緒，可進行測量。
- All the features of the Fluke Calibration 2100 Controller
- Installs easily
- Two independent over-temperature cutout circuits
Fluke Calibration’s bath controllers have long been recognized as being among the finest in the world. They’re the most popular retrofit controller in the industry, and now they’re available for Rosemount baths. The Model 7900 Controller installs easily and can replace the Rosemount Model 915 for all Rosemount bath models.
This controller uses the same circuitry as Fluke Calibration’s 2100 Controller to achieve long-lasting stabilities of ± 0.003 °C or better. Special noise-rejection techniques allow the 7900 to measure the very tiny resistance changes required for this level of stability. AC bridges are used within the controller to cancel thermal EMFs. Custom high-precision resistors contribute to short- and long-term stability and advanced filtering techniques force out troublesome line noise. The Model 7900 includes a special circuit that monitors the controller’s microprocessor and automatically resets it if its operations are interrupted. Two separate cutout systems are also included for keeping your bath’s temperature within its normal range.
A software cutout uses an adjustable high-temperature limit that can be easily accessed through the front panel and set to match the requirements of your bath fluid. Should the control sensor measure a temperature beyond this upper limit, heating is shut down. If the bath’s temperature falls below its normal operating range, the heaters are turned on and the LN 2 cooling is shut off. A second, independent hardware cutout monitors the bath’s temperature with a thermocouple and shuts down all heating and LN 2 cooling if the bath’s temperature rises above its range.
These cutout features, combined with the superior reliability and long-term stability performance of the 7900, allow you to run your system for as long as you like between shut-downs—365 days a year, if you wish. Your bath can be ready for you to take measurements the minute you walk into your lab each day.