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XPS Excitation Control Switch for 4-20mA Transducer Circuits

Power control for external transducers

The XPS Excitation Power-Saver Switch is a special feature on selected Spectrum 4000 Current Loop data loggers that minimizes power consumption and extends the life of external battery-powered 4-20mA transducer circuits.

The XPS was developed for remote two-wire 4-20mA transducer monitoring applications where no line power source is available. The switch allows users to connect one or more transducers to their data logger, power them with an external battery, and have the circuit last for an extended period of time without premature draining of the battery.

An internal software-controlled switch, the XPS features a user-adjustable transducer warm-up time to ensure stable and accurate transducer operation.

How it works - XPS Switch operation

	The XPS switch works by opening the transducer and external battery circuit between readings. The switch then closes the circuit a pre-set time prior to each reading to allow for transducer warm-up and stabilization.

Extends transducer battery life significantly

	By cycling the power in between readings, transducer battery energy is conserved for extended monitoring sessions.

Typical setup

A typical remote datalogging setup using the XPS switch consists of a Spectrum 4000 Current Loop data logger, a two-wire 4-20mA transducer (i.e. pressure, flow, PH, etc.) and an external battery pack to provide transducer excitation.

The following diagram shows a typical setup diagram for a two-wire 4-20mA current transducer:

XPS Connection Diagram

Specifications

Models:	XPS Switch is included on the following data logger models: 4000 (channels 1 and 3 only), 4000-1CW, and 4000-4CW (channels 1 and 3 only).
Warm-up Time Periods:	Programmable (in intervals of 10 seconds) from 10 seconds to 40 minutes.
Maximum Voltage:	30 volts DC
Input Impedance (On):	50 ohms
Circuit Protection:	Over-current protection to 60 mA.