IEC 60519-7 pdf download Safety in electroheat installations – Part 7: Particular requirements for installations with electron guns
7.1 Manual earthing device
After switching off the high-voltage supply and gaining access by opening the door of theelectron gun chamber or the housing of the electron gun, a portable earthing device of anapproved design shall be used to remove any remaining charge before touching parts, whichare normally live during operation.
The highly flexible earth conductor of the portable earthing device shall be permanently fixedto its earthing point. This earth connection point shall be visible for easy checking by theoperator and be clearly and durably marked.
7.2Mechanical earthing system
Alternatively, a mechanically self-acting earthing mechanism that is activated by themechanical action of opening the gun chamber may be installed，provided that the properfunction of this self-acting mechanism can be easily checked by eyesight from a safe distance.
7.3Automatic earthing system
Alternatively,an automatically operating earthing mechanism may be installed under thefollowing conditions:
a) the mechanism is automatically activated when the gun operation is stopped;
b) the proper functioning of the automatic mechanism is detected by a fail-proof automaticdetection system;
c) a signal visible to personnel opening the gun chamber indicates proper functioning of the automatic earthing system;
d) an electro-mechanic lock of approved design disables opening of the gun chamber beforethe proper functioning of the earthing device has been positively detected.
Also, in the immediate vicinity of the high-voltage supply(ies), portable earthing devices shallbe installed so as to be clearly visible.
8.1 High-voltage feeder cables
The high-voltage feeder cables shall be adequately insulated and efficiently protected againstmechanical damage.
Shielded cables shall be used for the high-voltage feeders or the feeder cables shall beinstalled inside conductive conduits or flexible hoses.Cable shields,conduits or flexible hosesshall be connected to the equipotential bonding.
When high-voltage feeder cables are laid inside conduits or flexible hoses, other cables shallnot be included, except a return conductor. Each electron gun shall have its own conduit orflexible hose.
lf the high-voltage feeder cable runs inside a conduit or flexible hose, the conduit or flexiblehose shall extend into the high-voltage terminal connection compartment.
High-voltage feeder cables and low-voltage cables may run together inside cable trenches or cable troughs providing the high-voltage feeder cables are protected mechanically and electrically. The cable trenches or troughs are not considered as protection.