What about power for the ONE Series?

Posted on January 7, 2021 by David Bonyuet in: Gas | Safety | Smart Switches | Technology

The ONE Series was designed to work with the leakage current from process controllers, and therefore it is a specialized switch like no other: it brings the benefits of electronic switches and smart sensors, with no extra penalty on additional power wiring.

The final user can just replace their mechanical switch by the ONE series and then their process can reap all the benefits of intelligent instrumentation.

Mechanical pressure and temperature switches do not have an equivalent power requirement, and therefore need further explanation. The ONE Series (1XSWLL, 1XSWHL / HH) can take the PLC digital input to transmit the switch condition.  It will also be the power source for the device.  As one customer said, “this is like magic”.

There are no hidden batteries! No extra wiring for power is required for the ONE series.

The ONE Series connects to the PLC/DCS discrete input, to report the pressure/temperature switch condition (whether open or close). This setting can be programmed locally through the device menu.  The user can set it to be normally open, or normally closed to fit their configuration needs.

In order to harvest energy from the PLC/DCS input, the ONE Series needs to be selected based on the target application.  Is this a PLC low voltage DC input? or a high voltage input?  The high voltage version can work with DC or AC from 70 to 240 V.  The low voltage version is only DC from 7.8 V to 50 VDC.  There is an additional condition, the PLC input must be able to feed a certain load (and many of them can): for the low voltage version, they should provide at least a 750 uA (0.75 mA) and for the high voltage version, it must be able to feed a 1 mA (0.1 A) load.

Usually PLCs/DCS will disclose the current on the input terminal for logic, 1 (one) and for logic 0 (zero).  The important parameter to validate is that the controller can supply at least 1 mA for the zero state, otherwise a bench testing might be required.  You can also contact United Electric Controls, and our expert customer sales force will handle the question for your configuration.

There is ONE series for 4-20 mA loops with a big HART (1XTXSW or 1XTX00).  In the same way, this one powers from the loop itself.

The ONE Series can also be powered directly with a power supply. However, the user should put the resistor that comes with the package.

The benefits of smart electronic instrumentation can help upgrade your current mechanical switches throughout your plant, without impacting your current wiring.  Just replace the mechanical pressure or temperature switch with the ONE Series.  This enhancement will provide a local display for your process. Functionalities that help support your process troubleshooting together with a configurability, that reduces your MRO inventory and simplify your maintenance program eliminating the needs for periodic calibration.

About the Author:
David Bonyuet, Design Engineer
David has over 20 years of experience in engineering.

Email: DBonyuet@ueonline.com

one series

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