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METTLER TOLEDO Weigh Module Systems Handbook

(12/99)3-10

Determining System

Resolution

The ability of a combination of load cells and indicator to give the desired system

resolution or increment size can be determined by the following formula:

Signal Strength

Desired Increment Size × Load Cell Output (mV/V)* × Excitation Voltage** × 1,000

(Microvolts per Increment)

Individual Load Cell Capacity × Number of Load Cells

*Most METTLER TOLEDO load cells have an output of 2 mV/V.

**See Table 3-2 for excitation voltages.

Enter the desired increment size into the formula, along with the load cell and indicator

parameters. If the signal strength (microvolts per increment) exceeds the minimum

allowed for the indicator, the system should be able to deliver the desired resolution.

Indicator Excitation Voltage Minimum Microvolts per

Increment (multiple cell)

Maximum Number of

Displayed Increments

Jaguar® 15 VDC 0.1 100,000

Lynx® 15 VDC 0.1 50,000

Panther® 5 VDC 0.6 10,000

Puma® (Hazardous Area) 1.6 VDC 0.05 25,000

Table 3-2: Resolution Limitations for METTLER TOLEDO Indicators

Example

Suppose a tank scale has four 5,000-pound load cells (2 mV/V) attached to a Jaguar

indicator. You want to be able to weigh up to 15,000 pounds at 2-pound increments

(7,500 displayed increments). Use the formula to determine the required signal

strength:

2 lb × 2 mV/V × 15 VDC × 1,000

5,000 lb × 4

According to Table 3-2, the minimum allowable signal strength for a Jaguar indicator is

0.1 microvolt per increment. Since the 3.0-microvolt signal derived from the formula is

above this 0.1-microvolt minimum, you should be able to display 2-pound increments.

= 3.0 microvolts per increment

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Mettler Toledo LJ16 Spécifications Page 25