Laboratory manual for the evaluation of non-automatic weighing devices
LG-3.09 DC Voltage variation
Table of contents
Sections 9, 10, 11 and 27 of the Specifications Relating to Non Automatic Weighing Devices (1998)
This test is performed on any complete electronic devices or major electronic components that operate from a DC power source (Batteries or other DC sources, but not through an AC/DC adapter). Self-powered weighing elements will be submitted to this test. Voltage variations are susceptible to occur during the normal use of devices. The purpose of this test is to ensure that voltage variations do not adversely affect the device performance and normal operating characteristics. DC power operated devices must continue to operate normally despite of a power reduction to the point where no weight indication is provided and power increase by 10% of the nominal value.
- AZT may be in any status. If "on", it must be set to the lowest value; if zero is the lowest selectable value, it will be set to zero. The amount that the AZT may track at once may not be set to a value larger than 0.6d which is the maximum value allowed by the Specifications.
- If the IZSM range does not exceed 20% of Max, tests will be performed with the IZSM set at the upper limit of its range.
Note: In the case of a multi-range device, it is 20% of Max of the lowest range; in the case of a multi-interval device, it is 20% of max of the first range.
- If the IZSM range exceeds 20%, tests will be performed twice: a first series of tests using the lighter platter provided by the applicant and the second series with the IZSM set to the upper limit of its range.
- The weighing device must be leveled to its reference position.
- The device must be set for the maximum capacity and smallest verification scale interval for which the approval is sought.
- If so equipped, the "enhance resolution feature" of the device will be used during the tests. If this feature is not available, use the small weight method to determine the device errors before rounding.
- This test is performed at ambient temperature (±20°C); or at the mid point of the temperature range if significantly different from 20°C; and ±50% RH.
- Power source must be stable to within ±2%
- Let the Power Supply and the DUT warm up for the minimum time recommended by the manufacturer.
- Decrease the voltage until the device ceases to provide a weight indication. Increase the voltage until the device resumes the indication; re-zero.
- Perform an increasing and decreasing test and record the results.
- Activate the device functions to ensure they operate normally (tare, printing, motion detection, etc.)
- Record the following data:
- relative humidity,
- errors, and
- note any malfunctions of the features.
- Increase the power supply voltage up to 10% above the device nominal voltage; re-zero and repeat steps 3, 4 and 5
Note: It may be necessary to increase the voltage beyond the limit point of display, and then decrease the voltage in order to be able to reach the lowest voltage at which an indication is provided.
Some devices have an extended voltage range, for instance from 12 to 72 DC volts. In such a case, the device will be tested at the lowest voltage where a weight indication is provided and 10% above the high limit of the voltage range.
Interpretation of results
The DUT is deemed to have met the requirements if during the voltage variations the device:
- operates within the prescribed limits of error and all the functions operate normally; or
- ceases to display weight and price values and prevents the transmission and storage of data.
- Rev. 1 (March 2010)
- AZSM renamed to AZTM
- Formatting change
- Removed requirement for an increasing/decreasing test at nominal voltage
- Date modified: