But there is a problem, and that is when the 'appliance' is not self contained. A cooker is fine, power goes in, raw food goes in, burnt mess comes out. That is what it is supposed to do. (I prefer to cook on a fire myself but that is a side note and just a matter of familiarity)
In the case of the separated motor and the VSD, (or nearer home, the heating system and the circulating pump) it may well be that each installation is very different, and the design authority is the individual who put it in, and may well not be available for comments. How a committee meeting that is separated from that design and installation in both time and space can claim to know it better is beyond me.
If the VSD data sheet says it meets IEC 61800-5-1, then you know short circuit protection been considered, or at least whoever printed the data sheet thought it had been.
But even if not, so llong as the designer ensures the Earth path to the motor is adequate to avoid a dangerous condition with a dead short to a live conductor, then any fault where a line shorts to earth at the motor, but then in the VSD a few ohms are added in series with the live core cannot cause a danger either - and that is the only credible fault mechanism.
You cannot sensibly protect against a person being connected between the motor phases any more than you can if they are connected L-N on a normal circuit.
But there is a problem, and that is when the 'appliance' is not self contained. A cooker is fine, power goes in, raw food goes in, burnt mess comes out. That is what it is supposed to do. (I prefer to cook on a fire myself but that is a side note and just a matter of familiarity)
In the case of the separated motor and the VSD, (or nearer home, the heating system and the circulating pump) it may well be that each installation is very different, and the design authority is the individual who put it in, and may well not be available for comments. How a committee meeting that is separated from that design and installation in both time and space can claim to know it better is beyond me.
If the VSD data sheet says it meets IEC 61800-5-1, then you know short circuit protection been considered, or at least whoever printed the data sheet thought it had been.
But even if not, so llong as the designer ensures the Earth path to the motor is adequate to avoid a dangerous condition with a dead short to a live conductor, then any fault where a line shorts to earth at the motor, but then in the VSD a few ohms are added in series with the live core cannot cause a danger either - and that is the only credible fault mechanism.
You cannot sensibly protect against a person being connected between the motor phases any more than you can if they are connected L-N on a normal circuit.
