Old Glasgow Excel 200 Amp. 3 Phase fused switch.

I believe that the blades on the square section rotating shafts have to be manually set for correct operation. A new shaft with affixed blades from one fused switch may not work correctly in another fused switch of the same catalogue number. I did notice that after lubrication the ON indicator flag showed correctly in the observation window, before lubrication it seemed not to be fully showing, and a part of the OFF indicator was showing, indicating that perhaps the switch was not fully closed.


I stumbled upon this advice from the H.S.E.


Design rating and system modifications 21 Switchgear is described as being ‘overstressed’ when it is operated beyond its design rating. This could be due to excess load or where the fault energy (the energy that the switchgear would need to carry, make or interrupt in the event of an electrical fault) exceeds the capability of the switchgear. If required to operate under these conditions, overstressed switchgear may not cope with the electrical, magnetic and thermal stresses imposed upon it. This can result in it failing catastrophically with the potential to cause injury. Switchgear must not be used where its strength and capability may be exceeded, unless it is used in such a way that nobody could be exposed to danger. 22 When originally installed, switchgear should have been adequately rated for the duty it was intended to perform. Changes to an electrical system can result in switchgear becoming overstressed. Careful consideration must be given to system modifications to ensure that dangerous conditions are not created. Changing the configuration of a system through switching operations that put transformers into parallel operation can result in an increase in fault energy. Such arrangements may result from a response to abnormal system conditions or be necessary during planned maintenance work. Interlock systems should be used to prevent overstressing in such circumstances. Where it is not possible to use interlocks, clear operating instructions must be provided to prevent configurations that have the potential to overstress switchgear.


Z.

I believe that the blades on the square section rotating shafts have to be manually set for correct operation. A new shaft with affixed blades from one fused switch may not work correctly in another fused switch of the same catalogue number. I did notice that after lubrication the ON indicator flag showed correctly in the observation window, before lubrication it seemed not to be fully showing, and a part of the OFF indicator was showing, indicating that perhaps the switch was not fully closed.


I stumbled upon this advice from the H.S.E.


Design rating and system modifications 21 Switchgear is described as being ‘overstressed’ when it is operated beyond its design rating. This could be due to excess load or where the fault energy (the energy that the switchgear would need to carry, make or interrupt in the event of an electrical fault) exceeds the capability of the switchgear. If required to operate under these conditions, overstressed switchgear may not cope with the electrical, magnetic and thermal stresses imposed upon it. This can result in it failing catastrophically with the potential to cause injury. Switchgear must not be used where its strength and capability may be exceeded, unless it is used in such a way that nobody could be exposed to danger. 22 When originally installed, switchgear should have been adequately rated for the duty it was intended to perform. Changes to an electrical system can result in switchgear becoming overstressed. Careful consideration must be given to system modifications to ensure that dangerous conditions are not created. Changing the configuration of a system through switching operations that put transformers into parallel operation can result in an increase in fault energy. Such arrangements may result from a response to abnormal system conditions or be necessary during planned maintenance work. Interlock systems should be used to prevent overstressing in such circumstances. Where it is not possible to use interlocks, clear operating instructions must be provided to prevent configurations that have the potential to overstress switchgear.


Z.