Instruction Manual

Calibrating the 4-20 mA Proportional Output

You must calibrate the speed switch if the standard proportional output of 4 to 20

mA is changed to :

0–5 Vdc using switch C1, or

0–10 Vdc using switch C2

To calibrate the new proportional output

1 Attach a digital voltmeter to terminals 9 (–) & 10 (+).

2 Apply 10% of the full-scale frequency to input terminals 5 (+), 6 (–).

3 Adjust the PROP OUT ZERO adjust potentiometer (See Fig. 4-10,

below) to yield 10% of full-scale proportional output on the

voltmeter.

4 Apply 100% of full-scale frequency to terminals 5 (+) & 6 (–).

5 Turn PROP OUT SPAN adjust potentiometer (See example below)

to yield 100% of full-scale proportional output on the voltmeter .

6 Repeat steps 2, 3, 4, and 5 three or four times to assure accuracy.

Chapter 4

Fig. 4-10 The PROP OUT

ZERO and PROP OUT SPAN

adjustments are located in

the upper right corner

under the top plate of the

SST-2000A/H.

EXAMPLE: A unit calibrated for 0–500 Hz input is being

recalibrated to 0-10 Vdc proportional output (from 4–20

mAdc proportional output).

♦ Apply 10% of full-scale (50 Hz) to terminals 5 (+) & 6 (–).

♦ Adjust PROP OUT SPAN adjust potentiometer to yield

1.000 Vdc on the voltmeter.

♦ Apply full-scale frequency (500 Hz) to terminals 5 (+) &

6 (–).

♦ Turn PROP OUT ZERO adjust potentiometer to yield 10.00

Vdc.

♦ Repeat 3 or 4 times for accuracy.