Frothingham Electronics Corp Customer Support

• Support Home
• FEC200
• SC924
• CV300B
• VF40D
• PLS1000CM
• Scan500
• FreeDOS
• Thermal Testing

Schematics Introduction:

Tests and Programs:

Accuracy/Calibration: Specifications Calibration Overview Calibration Step-by-Step Step-by-Step .pdf file

Troubleshooting: Introduction Schematics

FEC Home > Customer Support > PLS1000CM Support > Calibration & Specificaitons >Calibration Overview

PLS1000CM CALIBRATION

OVERVIEW

The calibration of the PLS1000CM (and other testers in the PLS family) consists of verifying the scale factors of the voltage readout scales by direct comparison with an accurate certified DC voltmeter. Also verify the power supply scales by measuring the voltage across accurate certified resistors and calculating the current by Ohm’s Law. The lower current scales can use the standard voltmeter to measure across the resistors. The higher current scales use the pulse reading voltmeter contained in the tester, which has first been verified by comparison with the standard DC voltmeter.

There are provisions for adjusting the zero offsets of some pulse current scales and one voltage scale by setting offset values in the tester’s firmware.

Except for these offset adjustments, there are no other adjustments to be made. The tester is designed to stay within its specified accuracy indefinitely and failure to do so is considered a failure that needs to be repaired.

The resistors used should be certified to be correct within 0.05%. Otherwise you need to make corrections for the known deviations of the resistors.

---

DETAILED PROCEDURE

First set the offsets in the firmware, voltage first, then current, using the procedures described below.

VOLTAGE OFFSET Using an accurate 4-terminal 1 Ohm resistor as the DUT, set up a VF test at 1A with a 1mS pulse width. Record the reading. The reading should be approximately 1.000V but the actual observed reading is what you will use. Now replace the 1 Ohm with a 0.01 Ohm (10mOhm) 4-terminal resistor. Repeat the VF test. The reading should be 1/100th of the reading recorded above within ± 1 digit. (Of course there may be some rounding related to dividing by 100. Use the nearest digit. For example, if the first reading is 0.998V, the expected low reading would be 0.010 Volts.) Readings from 0.009 to 0.011 are ok. If the error is greater than that, then the Voltage offset should be adjusted.

To access the offset adjustments, first press the “reset” button on the front panel or cycle the power off then on. Then press the “1” key on the keypad. First you will see offsets labeled: Offset_1, then -2, then -3. Skip over these by pressing the # key to accept the current setting. Then you will come to “Read offset.” Note the current setting then press * to indicate you wish to change it. Then enter a new value to correct the error noted above. Each digit changes the reading by 1mV. Press # to accept your new setting and then repeat the test above to confirm that you have corrected the offset. You will use this procedure again later with some minor changes to correct current offsets 1, 2, and 3.

CURRENT OFFSETS 1, 2 For currents between 6A and 25A, the tester uses pulser 1 and pulser 2 alternately. It is important to keep track of which pulser is being used so that the correct offset is being adjusted. After a “reset,” pulser # 1 will be used first. These tests will use VF tests with pulse widths of 1mS. The DUT will be a 100mOhm resistor. The currents will be 6.1A and 24.4A.

First reset the tester (or cycle the power off/on) the set up VF at 24.4A, 1mS. <3V using the 100mOhm resistor. Take and record two readings, #1 and #2. Now reset the tester again and set up VF at 6.1A, 1mS >3V.

Take two more readings. #1 and #2.

The second set of readings should be 25% of the first set ±2 digits. If not, you should perform a firmware offset adjustment similar to the voltage offset except adjust Offset 1 and/or Offset 2. Be sure to run the tests above again to check your adjustments and repeat if necessary.

CURRENT OFFSET 3 Above 25A, both pulsers are used in parallel. The offset adjustment is similar. Use a VF test with a width of 1mS. With 10mOhm and 100mOhm resistors. First set up VF at 300A, 1mS, <3V with the 10mOhm resistor. Record the reading.

Now change to 30A, 1mS, <3V with the 100mOhm resistor. Record the reading.

The readings should be the same within 10mV. If not, perform the firmware adjustment for Offset 3 and then recheck and repeat if necessary.

CALIBRATION CHECK After successfully completing the preceding Offset adjustment, the operation of the tester should be checked using the calibration check form.