Features and Benefits:
- Accuracy. The VEL-trol II is designed to maintain an accuracy of 0.1% of Natural Span. For a span of 0 to 0.05 IN w.c., this accuracy is equivalent to an output accuracy of ±0.00005 IN w.c. differential pressure or 0.45 FPM velocity at span.
- Continuous Display of Process. All VEL-trol II’s are equipped with a 2×20 liquid crystal display (LCD) for use during the configuration and calibration process, and to display one transmitter output during normal operating mode. The VEL-trol II offers an optional multi-line, backlit, graphical LCD providing up to four lines of data display, with each line individually scalable in user selectable format and units of measure. For high visibility, the main process variable (flow) is displayed with easy-to-read, triple-size digits. Other process variables are displayed with standard size digits.
- Analog Communication. Each analog input and output signal can be individually configured for 0-5VDC, 0-10VDC, or 4-20mADC by means of a single jumper.
- Electronic Respanning. The VEL-trol II operating span can be electronically selected anywhere between the Natural Span and 40% of Natural Span, without having to perform recalibration involving an external pressure source.
- Primary Signal Noise Filter. To eliminate background noise and pulsations from the flow signal, the VEL-trol II is equipped with a user selectable digital low pass filter.
- High Turndown Ratio Operation. The VEL-trol II, with its high level of accuracy and automatic zeroing circuitry, can maintain linear output signals on applications requiring velocity turndown of 10 to 1 (equal to a velocity pressure turndown of 100 to 1).
- Microprocessor Based Functionality. The VEL-trol II’s on-board microprocessor performs the functions of operating parameter selection, transmitter configuration, input/output and display signal scaling, and transducer calibration. Imbedded software performs span, flow, and 3-point “K” factor calculations. Input to the micro-processor is via pushbutton.
- AUTO-purge Management (optional). For “dirty air” applications requiring the use of an Air Monitor AUTO-purge system, the VEL-trol II provides the capabilities of establishing purge frequency and duration while giving the user a choice of either internally timed cycle frequency or externally triggered purge initiation. During the purge cycle all transmitter outputs are maintained at their last value prior to the start of the purge cycle.
- Control of Extreme Dynamics. The VEL-trol II incorporates a controller into the ultra-high accuracy VEL-trol II transmitter providing the three modes of proportional, integral reset, and inverse derivative to permit the controller to be tuned to the extreme dynamics of critical airflow and pressurization control processes. When integrated with a Soft Start feature it allows to force close the control damper when system is non-operating or switched OFF.
- Special Functions and Alarm Capability. The VEL-trol II is capable of performing one of five special application functions using a second transmitter as an input: Summed flow, flow differential, low signal select, high signal select, or percent deviation. The special function output can be both displayed and provided as an analog output signal. Alarms related to the measured process can be configured for one of three modes: Low/Low, High/Low, and High/High. It can be configured for a Special function Control also.
- Multiple Operating Power Selections. Standard input power supplied to the VEL-trol II can be either 24VAC or 24VDC via automatic selection. An optional 120VAC external power transformer (UL listed) can be provided.
- NEMA 1 Enclosure Rating.
- CE Certification. For optional CE Certification, the VEL-trol II is furnished in a NEMA 4 enclosure.
