Tuesday, 31 May 2011 02:10 Last Updated on Monday, 29 August 2011 01:11 Written by Administrator

MODEL JH250: 2-WIRE TRANSMITTER
POTENTIOMETER INPUT, FIXED RANGE, NONISOLATED

    • Potentiometers from 1 to 100Kohms
    • Offset and Expanded Input Ranges Possible
    • Fits Standard Connection Heads
    • Quick-Check Output LED
    • -40 to +80 Degree C Operation
    • DIN Rail mounting available

    JH250
    PDF
    DATA SHEET

The Model JH250 2-wire transmitter provides a 4/20mA current loop output proportional to the position of a potentiometer or slidewire wiper. A fixed-range device, it is precisely calibrated to your specified input range at the factory. Standard input calibration is 0/100% travel: it may be readjusted or factory-calibrated to any 50% or wider portion of the travel. Conformal coating protects the circuitry against condensation and corrosion in industrial atmospheres.

The JH250 is a loop-powered device. Connected in series between a 24Vdc supply and readout instruments, it receives its power from the 4/20mA output loop. A built-in LED indicates loop current: dim at 4mA, bright at 20mA. The JH250 does not provide input/output isolation.

ORDERING INFORMATION

Model Number: 

Model JH250.
Input Range: 

Standard calibration is for 0/100% travel. If you wish, calibration can be factory-set for any 50% or wider input range. Simply specify on your order.
Input Potentiometer:  

It is not necessary to specify the potentiometer’s resistance. Just make sure it is no less than 1Kohm nor more than 100Kohms.
Output Range: 

(Always 4/20mAdc.)
Power: 

Always dc loop powered.
DIN-Rail Mounting:  

Change model number to Model JH250-DIN. (See "Installation and Connections," below.)

INSTALLATION AND CONNECTIONS

The JH250 is 1-3/4 inches in diameter and is designed to fit many standard thermocouple-type connection heads. It may also be mounted to any surface using two #8 (or smaller) screws. An optional DIN-rail mounting clip (specify Model JH250-DIN) allows the transmitter to be snapped onto DIN rail. Width is 1-3/4 inches.

Connections are made to the transmitter’s terminal strip. Connections are:

"+" Terminal: Output/Power Loop. Receives current from (+) DC supply. 
"-" Terminal: Output/Power Loop. Passes on current to the next series loop device, or to the (-) supply. 
Terminal A: Potentiometer wiper. 
Terminal B: Potentiometer cw (100% travel). 
Terminal C: Potentiometer ccw (0% travel).

DETAILED SPECIFICATIONS

Input Capability:  

0 to 100% travel, or any 50% or wider portion of the travel (for example, 25 to 75% travel).
Input Potentiometer:  

May be any resistance between 1Kohm and 100Kohms. It is not necessary to specify the potentiometer resistance on your order: end-to-end resistance does not affect the calibration.
Output:  

4/20mA, 2-wire (loop-powered) output.
Accuracy (factory calibration): 

+/-0.1% of span.
Adjustability: 

Zero and span provide sufficient adjustability to allow recalibration to any 50% or wider portion of the input potentiometer’s travel.
Linearity: 

+/-0.05% of span or better.
Response Time: 

Under 100 milliseconds.
Guaranteed Operating Temperature: 

-40 to +80 deg. C (-40 to +176 deg. F).
Temperature Stability: 

+/-0.02% of span per deg. C, or better.
Power Requirements: 

DC loop-powered. Requires at least 12Vdc at the transmitter’s output terminals. 36Vdc maximum.