3 five-point linear calibration – Rice Lake Condec UMC600 User Manual

Page 51

UMC600 Installation Manual

5.3

Five-Point Linear Calibration

There are five calibration points (La, Lb, Lc, Ld, and Le) that can be entered sequentially. Calibrations using fewer
than five points will linearize the curve up to the last data point. The curve is then extrapolated from the last entry
point. For best results, use values of 20%, 40%, 60%, 80%, and 100% of full scale for the five linearization points.

1. Turn on option 6 (see Section 4.6 on page 32).

2. After performing a zero calibration as described in Section 5.1, place the first test weight on the scale

platform. Allow ten or more seconds for stabilization (motion LED goes out).

NOTE: Straight averaging is applied during calibration.

3. Enter test weight value for the first calibration point using the numeric keyboard.

4. When the display is correct, press the

ENT

key. The display will read

CAL

briefly. The value of the last

calibration point entered then appears with a flashing display prompt

indicating the next calibration point

to be entered (Lb, Lc, Ld, or Le).

5. Repeat Steps 2, 3 and 4 for Lb, Lc, Ld, and Le with the appropriate test weights.

6. Recheck the zero weight by emptying the scale.

NOTE: AZM is off during calibration. Dead load display provides signal reference.

7. When complete, open all switches on SW1.

8. Re-install faceplate bracket and tighten the knurled fasteners. Seal the unit if used in a legal-for-trade

application.

Calculations Example

Capacity = 200,000 lb x 20 lb

Number of graduations = 200,000

÷ 20 = 10,000

Configuration:

•

Parameter 1 = 100 (10,000 graduations)

•

Parameter 2 = 20 (resolution)

•

Parameter 3 = 0 (no decimal point)

Other Factors to Note

PAZ: 1.9% x 200,000 = 3800 lb

Overrange: 103% x 200,000 = 206,000 lb

Minimum calibrated load: 10% x 200,000 = 20,000 lb

Analog Sensitivity

Analog signal input range: 0.7 to 3.2 mV/V

Analog signal sensitivity: 0.3

µV/graduations at 20,000

For H-44 requirements, use a factor of 4 (1.2

µV/grad). If the lower signal range is used for calibration, the indicator

may fail acceptance testing with 0.3

µV/grad.

NOTE: Check for a minimum live load of 12 mV for 10,000 graduations. If less than 12 mV, decrease the number of
graduations accordingly.