Electrical outages. cyber attacks ?

Here is a suggestion for a test or investigation that a forum member might be able to carry out with suitable data logging/recording test instruments.

Find a large and continually running induction motor, taking care that the mechanical load on the motor is constant at least in the short term. The motor must be directly connected to the mains and not via any form of variable speed drive.


Measure the power absorbed at very frequent intervals, several times per second and record this. Also measure and record the grid frequency at similarly frequent intervals. I suspect that a sudden drop in frequency will result in a significant reduction in power for a short time until conditions stabilise at the lower frequency.


Basic electrical theory shows that a frequency reduction will reduce the steady state power used by say an AHU drive. Lower frequency, reduced motor speed, reduced fan speed, less air moved, therefore less power used.

My suggestion is NOT regarding these steady state conditions, but is regarding the behaviour of induction motors under rapidly varying or transient conditions.

Here is a suggestion for a test or investigation that a forum member might be able to carry out with suitable data logging/recording test instruments.

Find a large and continually running induction motor, taking care that the mechanical load on the motor is constant at least in the short term. The motor must be directly connected to the mains and not via any form of variable speed drive.


Measure the power absorbed at very frequent intervals, several times per second and record this. Also measure and record the grid frequency at similarly frequent intervals. I suspect that a sudden drop in frequency will result in a significant reduction in power for a short time until conditions stabilise at the lower frequency.


Basic electrical theory shows that a frequency reduction will reduce the steady state power used by say an AHU drive. Lower frequency, reduced motor speed, reduced fan speed, less air moved, therefore less power used.

My suggestion is NOT regarding these steady state conditions, but is regarding the behaviour of induction motors under rapidly varying or transient conditions.