Relay testing

Testing is always a must-have step for almost any designs to verify the proper functionalities. Lately I’ve been working on some complex auto-restoration relay settings development. Had so much...

Posted by Yifan Wang on 20 February, 2022

Transformer inrush

When transformer is energized, winding currents could become substantially large to cause relay misoperation. Several factors could impact magnitude of the inrush current like the switching...

Posted by Yifan Wang on 08 December, 2021

Short circuit hand calculation

Sequence networks are useful for analysis of unsymmetrical faults. A little hand calculation never hurt. A simple system is assumed as below. Three phase fault at the end of L4 can be calculated...

Posted by Yifan Wang on 10 October, 2021

A solar monitor demo

Finally finishing up the solar demo system with real time online monitoring. The test setup is lightly loaded during the day. Every 2 minutes, there will be new data entries added in the local...

Posted by Yifan Wang on 14 September, 2021

A bit of battery test

A 12V 100Ah sealed battery from a few years ago has been collecting dust on the shelf for quite a while. Lately I tried to bring it back to life if possible for proper future use. Since I got a...

Posted by Yifan Wang on 10 September, 2021

Modbus Comm.

Modbus is a widely used simple and reliable protocol for SCADA systems in many industries. It follows master-slave mechanism. If there are multiple slave devices, daisy chain method could be used....

Posted by Yifan Wang on 02 September, 2021