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73xx v284 Firmware Release Notes

Product Line
ION73xx

Environment
Firmware

Resolution
This document outlines all the fixes completed for v284 firmware on the 73xx platform.

The v284 firmware release was prompted by the 73xx Accuracy Fire (400088) in 2008. The primary driver behind the improvements made in this project was low yields of 0.5 class meters from production.

Symptoms: The main cause of low yields of 0.5 class meters was failures of current and kW at lower currents (between 50-250mA). The power error performance (as a function of current magnitude) has been found to have very strong correlation to the current RMS error.

Fix: Changes to the meters accuracy algorithms were made including the addition of Linearity Calibration Constants. The additional calibration constants work to improve performance in the low current range.

The following Known Issues are issues logged against the 73xx family prior to this release. They are verified to be fixed as a result of work done in firmware release v284.

SCR 434: MU outputs do not update properly
The MU kW and kWh values do not update properly. In single element mode, if power is applied and then removed from the meter inputs, the MU registers retain the old values, indicating power is still present.

SCR 450: v280 exit gate failed
Meters used to verify v280 firmware failed exit gate verification testing. The meters performed poorly at -0.5 power factor at low current. Subsequent testing done on a new batch of meters passed.

SCR 463: Lost communication to meter after upgrade fail
The meter became unresponsive after an upgrade failed using ION Setup. Cannot communicate to the meter in serial or ethernet. Also, the display screen became blank. The meter must be cold booted to be functioning again.

SCR 464: 7300v281: kW error at low current
The kW uncertainties at 50mA and 60mA were larger than 1% (Class 0.5S spec limit).

SCR 467: 7300v281 failed in energy accuracy test at low current
This is similar to SCR 464. The reading at 50mA, 120V and unity power factor has an error larger than 1%.

SCR 487: RMS and power oscillate up to 1%
Using a three phase source, with frequency set to 60.000Hz (actual freq 60.0004Hz), the rms and power readings have a trend to oscillate over about 90s on a 7350 and about 35s on a 7330. The magnitude of oscillation varies with signal level and the phase-to-phase and meter to meter. The phase of the oscillation appears to vary with phase offset from V1 (all phase readings rise and fall together only if the input signal is tied together). By changing the inputs frequency by +/-0.05Hz, the period of oscillation varied greatly.

SCR 486: DC offset not removed properly from calculations
50VAC at 60Hz was applied to meter input V1 and 50VDC applied to V2. Both V1 and V2 read 50VDC on the power meter module. Another test with a DC shifted AC waveform showed similar symptoms affecting RMS and power.

SCR 494: Cal pulser uses code with rounding error
The calibration pulser uses code that has a rounding error which results in up to 4ms of jitter. The problem may be less noticeable on this platform because it has 10ms resolution. This is the same issue as found on the 8600 platform, detailed in SCR 401.

SCR 497: Cal pulser not accurate when load varies
When the load varies, the calibration pulser is not accurate. An example is if the input power is 1.00W at the start of the test and 1.01W at the end of the test. If the test duration is 10s, the error will be (at least) 0.2%. This is the same issue as found on the 8600 platform, detailed in SCR 412.

SCR 498: Cal pulser net accumulation mode uses absolute algorithm
The module's "net accumulation" mode is implemented exactly the same as "Absolute accumulation". Common situations where this could be a problem is for VARs near unity PF, del-rec Watts, and (unconfirmed) watts near 0.5PF on a delta system. This is the same issue as found on the 8600 platform, detailed in SCR 410.

SCR 505: Vll not reported correctly when DC offset is applied
When a DC bias is applied, the reported Vll is incorrect. The magnitude of the reported error seems to be based on the magnitude of the applied DC offset.

SCR 506: THD is not measured correctly in Direct Delta
The meter measures and reports line-to-ground THD for V1, V2, and V3. It should be reporting line-to-line THD.

NOTE: See FA307723 for the entire firmware revision history.