current transducer 4 to 20ma output factory

Current transducer 4 to 20ma output factory how to#

For instance, the BAPI-Stat three-wire transmitter requires 10 mA of current to operate. Unlike a two-wire transmitter, a three-wire transmitter will consume more current from the system power supply than the 20 mA signaling current because the transmitter itself requires some current to operate. The three-wire transmitter’s common must be connected to the controller’s common.įigure 4 shows the most basic three-wire transmitter with one 4 to 20 mA signal. The transmitter contains a current source that provides signal current proportional to the physical property being measured. Three-wire transmitters are supplied with power and ground separate from the 4 to 20 mA current signal. Some of BAPI’s current transmitters are three-wire devices, such as the BAPI-Stat room unit. Three-Wire Transmitter with One 4 to 20 mA Signal The shield of the cable is connected to the controller ground and the negative terminal of the VC350A.Ĥ.

The Black or signal terminal of the transmitter is connected to the controller’s analog input which is factory configured to accept a 4-20 mA signal. The positive output of the VC350A is connected through a cable to the Red or positive terminal of the transmitter. The VC350A should be mounted as close as possible to the controller.

Current transducer 4 to 20ma output factory how to#

Figure 3 shows how to create the 4-20 mA current loop circuit for this particular circumstance.Ī 24 VAC transformer provides power to the controller and BAPI VC350A voltage converter used in the example below as the current loop power supply. When the controller’s peripheral power supply current limit is reached, an external power supply is needed to power additional sensors. The larger controllers that have DC power supplies to power sensor peripherals cannot supply unlimited power. The shield of the cable is connected to the controller ground. The Black or signal terminal of the transmitter is connected to the controller’s analog input which is factory configured to accept a 4 to 20 mA signal. The VDC output of the controller is connected through a cable to the Red or positive terminal of the transmitter. Figure 2 shows how to create a 4 to 20 mA current loop circuit for this style of controller.Ī 24 VAC transformer provides power to the controller. Many larger controllers have DC power supplies to power sensor peripherals and also have dedicated 4 to 20 mA inputs. The signal voltage will be 2 volt at 4 mA and 10 volts at 20 mA. If the controller’s analog input is configured for 0-10 VDC, then the load resistor should be 500Ω. The signal voltage will be 1 volt at 4 mA and 5 volts at 20 mA. If the controller’s analog input is configured for 0 to 5 VDC, then the load resistor should be 250Ω. A load resistor is connected from the analog input to ground. The shield of the cable is connected to the controller ground and the negative terminal of the VC350A. The Black or signal terminal of the transmitter is connected to the controller’s analog input. Figure 1 below shows how to create a 4 to 20 mA current loop circuit for a controller without a dedicated power supply or an input for a 4 to 20 mA signal.Ī 24 VAC transformer provides power to the controller and the BAPI VC350A voltage converter used in the example below as the current loop power supply.

At the same time, many of the best sensors in the industry are only available as a 4-20 mA output. Many low cost HVAC/R controllers do not include a dedicated power supply or a factory configured input for a 4 to 20 mA signal. A three-wire transmitter with two independent 4 to 20 mA signals. A three-wire transmitter with one 4 to 20 mA signalĥ. A two-wire transmitter with external power and a 4 to 20 mA inputĤ. A two-wire transmitter with controller power and a 4 to 20 mA inputģ. A two-wire transmitter with external power and an external resistorĢ. This document describes five of the most basic 4 to 20 mA current loop configurations:ġ.