NS1250N ML5.0E not reading frequency and showing zero Power readings.
Issue: Micrologic 5.0E displays NaN when reading frequency and shows zero power readings when the current is below a certain threshold.
Product Line: Micrologic E trip units installed with Compact NS breaker
Environment: Micrologic E Trip Units
Resolution:
According to the user guide,Micrologic E trip units do not support frequency display. Therefore, frequency values are not available when using this trip unit.
For confirmation, please refer to the provided link, page 66.
https://download.schneider-electric.com/files?p_Doc_Ref=DOCA0218EN&p_enDocType=User+guide
A check of the register list for Compact NS breakers (refer to the attached screenshot) confirms that Compact NS units equipped with Micrologic E trip units do not support frequency display. As a result, the frequency register returns NaN.
In the register table, the A/E/P/H column applies to NT/NW and NS breakers. This table indicates that only P and H trip units support frequency measurement and display on the registers. Micrologic E trip units do not include this capability.
For further details, please refer to the linked document, page 91.
For the Issue regarding incorrect power readings:
On Micrologic 2.0E, 5.0E, and 6.0E trip units:
The power value displayed on the Micrologic E front display and transmitted via Modbus is reported as zero when the load current is below 0.07 × In, where In represents the rated input current.
The current value displayed on the Micrologic E front face and transmitted via Modbus is reported as zero when the load current is below 0.005 × In.
When the load current falls between 0.005 × In and 0.07 × In, and the voltage is non‑zero, the current and voltage values are displayed normally; however, the calculated power value remains zero.
As a result, in customer applications, power calculation effectively begins when the load current exceeds 0.07 × In (Ia).
Released for: Schneider Electric New Zealand
