SCADA, which stands for Supervisory Control And Data Acquisition, is the graphical user interface for an automation control system and is a critical piece of infrastructure that allows the plant operator to efficiently monitor and control the automated process. So imagine the chaos when the SCADA system suddenly dies! The operators are left blind and unable to properly control their plant. This is why it is absolutely critical to have a Disaster Recovery Plan for all SCADA systems.

It is not a case of IF a system will fail, it is a case of WHEN. SCADA systems are computer based and even the best system will fail at some point due to various reasons like;

Your SCADA Disaster Recovery Plan should start with asking a few questions to identify what sort of system you have;

We came across a situation recently on site where an induction motor being driven by a VSD at a reduced speed had the operators asking "Why is the motor running at the rated current but not at the rated power?"
It was actually a very good question and one that we thought we would share with you all.

First of all there are a few things to remember about a motor;

The most basic method of control for an induction motor on a VSD is the Volts per Hertz (V/Hz) method, also known as open-loop or scalar control. This is where the VSD controls the motor speed by maintaining a constant ratio between motor voltage and frequency, as the frequency of the motor is reduced so is the voltage by the same ratio to maintain a constant magnetic flux.

If we have a look at the motor power formula, we see that the speed of a motor (shown as rpm) directly effects the power of a motor;