Palmer Wahl PST550 Solar Industrial User Manual

Palmer Solar Industrial Thermometer PST550

Installa2on and Maintenance Instruc2ons

The Palmer Solar Industrial thermometer is manufactured with two separate sensors within the probe. The solar-powered display is independent of the transmi6er output. The transmi6er is a regulator that controls the milliamp current rela2ve to temperature when wired in a current loop, as shown in the wiring diagram (Figure 1). The milliamp range is from 4 mA at -50°C to 20 mA at

150°C and is propor2onal within this range. To convert the current to a voltage, a precision load resistor, R, is used in the current look, a 250 Ω resistor will have a voltage across equal to V = iR or at -50°C, V = 0.004 * 250 = 1 volt and at 150°C v = 0.020 * 250 = 5 volts. The chart below (Figure

2) show the rela2on of temperature, current, and voltage with the recommended 250 Ω resistors.

Calibra on

The thermometer is shipped already calibrated. If a field check or adjustment is necessary, the following is applicable:

Display Calibra2on: With the stem stabilized in a known temperature bath, mel2ng ice chips at 0°C (32°F) for example, or at the use temperature, remove the access plug on the back of the thermometer and with a small screwdriver adjust the poten2ometer on the back of the PCB.

Turn slowly and wait 10 seconds for the update before readjus2ng.

Transmi6er Calibra2on: Calibra2on parameters are adjusted electronically at the factory and the parameters loaded into the transmi6er. There is no further need for zero or span adjustment in the field. The transmi6er is programmed to provide the top range temperature reading should the sensor fail or be disconnected.

Side View

PD1012 March 2015

Back View

Figure 1

V

FOR RL=250Ω mA F C

1.0 4.0 -58 -50

1.2 4.8 -40 -40

1.4 5.6 -22 -30

1.6 6.4 -4

1.8 7.2 14

2.0 8.0 32

2.2 8.8 50

2.4 9.6 68

-20

-10

0

10

20

2.6 10.4 86 30

2.8 11.2 104 40

3.0 12.0 122 50

3.2 12.8 140 60

3.4 13.6 158 70

3.6 14.4 176 80

3.8 15.2 194 90

4.0 16.0 212 100

4.2 16.8 230 110

4.4 17.6 248 120

4.6 18.4 266 130

4.8 19.2 284 140

5.0 20.0 302 150

Palmer Instruments, Inc. • 234 Old Weaverville Road • Asheville, NC 28804 USA • Phone: (828) 658-3131 • Fax: (828) 658-0728 • www.palmerwahl.com