Could you overheat an electric motor remotely?
Discussion
Gary C said:
What an odd question.
Yes you could, microwave, induction, neutron beam, gamma beam, list goes on.
Some sort of context would be good, do you want to overheat the neighbours shower pump through the wall ?
Agreed. Is the question a theoretical or practical question?Yes you could, microwave, induction, neutron beam, gamma beam, list goes on.
Some sort of context would be good, do you want to overheat the neighbours shower pump through the wall ?
In theory you can, but if you have a motor that appears to have overheated the likelihood of someone attacking it with an external source is quite small.
Major Fallout said:
My neighbours starter motor packed up the same day mine did, and now my shower pump is intermittently running.
The really strange thing is it’s not wired up to the electricity.
Cue X-files music
Do you mean totally disconnected from the electricity ?The really strange thing is it’s not wired up to the electricity.
Cue X-files music
You don't live under a 400kV overhead line do you ?
Major Fallout said:
My neighbours starter motor packed up the same day mine did,
Hardly the most suspicious coincidence, there must be hundreds of starter motors that gasp their last every day.Major Fallout said:
and now my shower pump is intermittently running.
The really strange thing is it’s not wired up to the electricity.
You are mistaken. Motors do not run without electricity.The really strange thing is it’s not wired up to the electricity.
Major Fallout said:
A big ish motor like a starter motor or shower pump, would it be possible to damage it without touching it or connecting to it?
Induction? Emp?
and a shower pump is not bigish Induction? Emp?
Come to work and I will show you some bigish electric motors running on 11,000V pulling 5-10MW
There are approaches that can be used, but these involve tampering with the power to the motors, the load on the motors or the cooling of the motors.
Load tampering
Motors have a defined torque/load curve and generally offer some form of inherent speed regulation. As load increases, many motor designs will increase torque in order to attempt to maintain speed. The greater torque on the motor with regulated speed means an increase in motor power, and therefore an increase in waste heat production. An extreme example is that of a stalled motor which will draw an enormous amount of current, and rapidly burn out unless protection systems intervene to disconnect the power.
Cooling tampering
Motors of any significant size require forced cooling. In many cases, this is delivered by the motor itself, by the rotor driving an integrated fan (for air-cooled motors) or a water pump (for water cooled motors). However, these may be dependent on external systems. A good example of this is a typical vacuum cleaner motor. Blocking the suction hose will de-load the motor, as there are no pumping losses, reducing heat production. But the suction air flow is often used as the source of air to cool the motor, as it allows the primary air pump to perform both the cleaning function and the motor cooling function. By obstructing the air flow, cooling air is also obstructed and the motor will overheat quickly even in the deloaded state.
Power tampering
Heat generation is closely related to supply voltage. This is especially the case for many types of AC motor where exceeding the recommended voltage even slightly results in dramatic increases in heat generation. So, changing a voltage tap on a supply transformer to give a higher voltage may be sufficient.
Some motors are electronically controlled, where an electronic control system generated a controlled voltage/frequency to match the requirements of the motor and the currently desired speed/acceleration profile. These can often be computer controlled. This approach was used in a cyber-attack on an Iranian nuclear facility. The facility used large numbers of high power, high speed motors which were electronically controlled. A carefully crafted virus was released which infected the computers supervising the electronic motor controllers, instructing the controllers to deliver power/speed beyond the motors capability, in an attempt to destroy the motors. (Look up Stuxnet for more info).
If you don't have electronic motor controllers, then 3 phase motors could be overheated by distorting the voltage waveform. Motors are designed to operate with a pure sine wave. Distortions can be treated as superimposed sine waves of different frequencies. In a 3 phase motor, frequencies (harmonics) which are (3n+1) * 50 Hz (i.e. 50, 200, 350, 500, etc.) will drive a 3 phase motor forward. Frequencies which are 3n * 50 (i.e. 150, 300, 450, 600) will generate heat but produce no useful torque. Frequencies which are (3n - 1) * 50 (i.e. 100, 250, 400, 550, etc.) will generate not just generate heat but will generate a braking torque, which will result in the motor drawing additional current (and generating addition heat) in order to overcome the braking effect. As it happens, 3 phase rectifiers which are used in things like industrial motor controllers, UPSs, etc. wherever large quantities of DC are required generate large current pulses. These current pulses cause voltage distortion as the voltage sags under the load. Most importantly, however, these pulses produce copious amounts of 250 and 550 Hz distortion. This equipment therefore requires filters which will mitigate these 250 and 550 Hz (5th and 11th harmonic) voltage distortions - for large industrial equipment, these filters are often procured and installed separately to the device generating the problem harmonics. Compromising these filters could be a sneaky way of degrading power quality at an industrial site sufficient to degrade motor performance. As sites may not perform routine voltage waveform monitoring, only voltage/current monitoring, this type of compromise may go unnoticed for some time.
Load tampering
Motors have a defined torque/load curve and generally offer some form of inherent speed regulation. As load increases, many motor designs will increase torque in order to attempt to maintain speed. The greater torque on the motor with regulated speed means an increase in motor power, and therefore an increase in waste heat production. An extreme example is that of a stalled motor which will draw an enormous amount of current, and rapidly burn out unless protection systems intervene to disconnect the power.
Cooling tampering
Motors of any significant size require forced cooling. In many cases, this is delivered by the motor itself, by the rotor driving an integrated fan (for air-cooled motors) or a water pump (for water cooled motors). However, these may be dependent on external systems. A good example of this is a typical vacuum cleaner motor. Blocking the suction hose will de-load the motor, as there are no pumping losses, reducing heat production. But the suction air flow is often used as the source of air to cool the motor, as it allows the primary air pump to perform both the cleaning function and the motor cooling function. By obstructing the air flow, cooling air is also obstructed and the motor will overheat quickly even in the deloaded state.
Power tampering
Heat generation is closely related to supply voltage. This is especially the case for many types of AC motor where exceeding the recommended voltage even slightly results in dramatic increases in heat generation. So, changing a voltage tap on a supply transformer to give a higher voltage may be sufficient.
Some motors are electronically controlled, where an electronic control system generated a controlled voltage/frequency to match the requirements of the motor and the currently desired speed/acceleration profile. These can often be computer controlled. This approach was used in a cyber-attack on an Iranian nuclear facility. The facility used large numbers of high power, high speed motors which were electronically controlled. A carefully crafted virus was released which infected the computers supervising the electronic motor controllers, instructing the controllers to deliver power/speed beyond the motors capability, in an attempt to destroy the motors. (Look up Stuxnet for more info).
If you don't have electronic motor controllers, then 3 phase motors could be overheated by distorting the voltage waveform. Motors are designed to operate with a pure sine wave. Distortions can be treated as superimposed sine waves of different frequencies. In a 3 phase motor, frequencies (harmonics) which are (3n+1) * 50 Hz (i.e. 50, 200, 350, 500, etc.) will drive a 3 phase motor forward. Frequencies which are 3n * 50 (i.e. 150, 300, 450, 600) will generate heat but produce no useful torque. Frequencies which are (3n - 1) * 50 (i.e. 100, 250, 400, 550, etc.) will generate not just generate heat but will generate a braking torque, which will result in the motor drawing additional current (and generating addition heat) in order to overcome the braking effect. As it happens, 3 phase rectifiers which are used in things like industrial motor controllers, UPSs, etc. wherever large quantities of DC are required generate large current pulses. These current pulses cause voltage distortion as the voltage sags under the load. Most importantly, however, these pulses produce copious amounts of 250 and 550 Hz distortion. This equipment therefore requires filters which will mitigate these 250 and 550 Hz (5th and 11th harmonic) voltage distortions - for large industrial equipment, these filters are often procured and installed separately to the device generating the problem harmonics. Compromising these filters could be a sneaky way of degrading power quality at an industrial site sufficient to degrade motor performance. As sites may not perform routine voltage waveform monitoring, only voltage/current monitoring, this type of compromise may go unnoticed for some time.
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