Did You Know?

Kele can handle all kinds of signal conversion applications.

In the building automation business, it's not uncommon to have requirements for analog signal conversion, signal scaling or signal isolation. The VFD driving a fan requires an isolated 4-20 mA signal but the controller only has grounded 0-5 VDC outputs available. A hot water valve and a chilled water valve, both with 4-20 mA actuators, are to be controlled in sequence from only one 4-20 mA controller output. Kele can provide the solution to these as well as many other signal manipulation applications with our VTI, UAT and DT13 products.

VTI Voltage to Current Converter
The VTI is a compact, low cost voltage to current converter. Any voltage signal from 1 to 19 VDC with a 1 VDC minimum span can be converted into a 4-20 mA signal. The 4-20 mA signal can be configured to be either direct or reverse acting. The VTI is also the solution to other applications. Adding an appropriate value resistor across its input terminals allows the VTI to accept milliamp signals as well as voltage signals. Two valves can be controlled in sequence by using two VTI's. The first VTI is calibrated to output 4-20 mA over a 4-12 mA input and the second VTI is calibrated to output 4-20 mA over a 12-20 mA input. The VTI incorporates an on-board reference voltage supply that can be used to power external sensing devices or transducers. This reference voltage supply is used when the VTI converts the resistance of a three-wire potentiometer into a 4-20 mA signal. The VTI is powered by 24 VDC, is factory calibrated and is small enough to mount in a standard handi-box. The VTI's versatility combined with its low cost make it ideal for common as well as unique signal conversion applications.

APPLICATIONS

• Convert 1-5 V, 6-9 V, 2-10 V, 3-15 V or any 1 V minimum span voltage signal between 1 and 19 VDC into a 4-20 mA signal.
• Re-scale a 0 ±1 mA or other milliamp signal with an external resistor
  into 4-20 mA.
• Convert a three-wire potentiometer resistance into a 4-20 mA signal.
• Sequence two valves or other devices using only one voltage or
  milliamp controller signal.
• Signal reversal, direct or reverse acting.
• Signal repeating or duplicating.

UAT Universal Analog Transducer
If the VTI is versatile then the UAT is truly universal. The UAT is jumper selectable for input signals in the range of 0 to 20 VDC and 0 to 40 mA (without an external resistor) as well as two-wire and three-wire potentiometers. These input signals are converted and/or scaled by the UAT and output in the range of 0 to 18 VDC or 0 to 20 mA. The output signal can be either direct or reverse acting. The UAT goes beyond the capabilities of the VTI by accepting input signals that start at zero, outputting either milliamp or voltage signals, providing both current and voltage reference sources for powering external sensors, accepting 24 VAC or DC power and allowing for easy field calibration. The UAT is available in both a snap-track circuit board version and an enclosed model that requires only 2"X4" of panel space.

APPLICATIONS

• Convert or re-scale 0-5 V, 1-5 V, 0-10 V, 2-10 V,
  0-15 V, 3-15 V, 6-9 V, 4-20 mA or most any other voltage signal from 0 to 20 V or milliamp signal from 0 to 40 mA into a voltage signal in the range of 0 to 18 V or milliamp signal in the range of 0 to 20 mA.
• Convert a two-wire or three-wire potentiometer into a voltage or milliamp output.
• Sequence two valves or other devices using only one voltage or milliamp controller signal.
• Signal reversal, direct or reverse acting.
• Signal repeating or duplicating.

DT13 Isolated DC to DC Transmitter
The DT13 is jumper selectable for milliamp or voltage inputs and provides a linearly transferred milliamp or voltage output. The DT13 input, output and power supply are all electrically isolated from each other making the DT13 useful for ground loop elimination and noise pick-up reduction. The DT13 contains conditioning circuitry that scales and filters the input signal and drives a precision isolator that carries the signal across the isolation barrier. The output side of the isolator drives a circuit that converts and/or scales the input signal into an output signal that is isolated and proportional to the input. The DT13 is designed to function in electrically noisy environments and can interface with recorders, data loggers, building automation controllers, HVAC controllers, variable speed drives, and other process or control system equipment.

APPLICATIONS

• Provide electrical isolation and signal conversion for 0-20 mA, 4-20 mA, 0-5 V, 1-5 V, 0-10 V, 2-10 V,
  0-15 V, and 3-15 VDC signals.
• Electrically isolated signal repeating or duplicating.
• Drive high impedance current loops up to 1000".