General
Equipment, in which the EIOs are used, should provide protection to personnel as described below. In addition, to protect the EIO, installation and operating precautions must be observed, and absolute ratings must not be exceeded.
Personnel
High Voltage
WARNING:
VOLTAGES REQUIRED FOR THE OPERATION OF EIKS CAN BE DANGEROUS AND POTENTIALLY FATAL TO PERSONNEL. EQUIPMENT MUST BE DESIGNED WITH PROTECTIVE DEVICES SUCH AS PHYSICAL SHIELDS AND FAILSAFE INTERLOCK CIRCUITS ON ACCESS PANELS TO PREVENT ACCIDENTAL CONTACT WITH HIGH VOLTAGE. SOME COLLECTOR DESIGNS OPERATE AT DEPRESSED VOLTAGE POTENTIAL. THUS, THE COLLECTOR BECOMES AN EXPOSED HIGH VOLTAGE SURFACE AND IS EXTREMELY DANGEROUS TO LIFE. COOLING SYSTEMS MUST BE DESIGNED TO PREVENT ACCIDENTAL CONTACT WITH THE HIGH VOLTAGE ON THE COLLECTOR. LIQUID COOLED AND AIR COOLED DEPRESSED COLLECTORS HAVE UNIQUE REQUIREMENTS TO ENSURE SAFE OPERATION OF THE EIK.
Air Cooled Collector Hazard
Installers and operators need to be aware of a potential high voltage hazard when operating air-cooled EIKs with depressed voltage collectors and the need to ensure that the installation presents no risk of electrical shock.
If the EIK collector is not directly grounded, and is to be operated either above or below ground potential, the the collector becomes an exposed high voltage surface. Contact with this surface can be fatal. The shaded area in Figure 1 indicates the high voltage surfaces on the collector.
The EIK must be installed inside a grounded enclosure. This enclosure must have provision to allow cooling air to flow past the EIK and prevent contact with high voltage surfaces of the collector by an operate/installer directly or with any type of tool.
Protective devices such as physical shields and failsafe interlock switch circuits, etc., must be installed and functioning to prevent physical contact with the collector.
Do not attempt to operate the EIK until it has been determined that all precautions have been taken to protect personnel from all hazards.
Liquid Cooled Collector Hazard
Installers and operators need to be aware of a potential high voltage hazard when operating liquid cooled EIKs with depressed voltage collectors and the need to ensure that the installation presents no risk of electrical shock. All coolants must be regarded as partial conductors of electricity. The following discussion assumes that the coolant lines are made of insulating material.
If the EIK collector is not directly grounded, and is to be operated either above or below ground potential, the coolant (in both flow and return lines) will equivalent to a resistor chain. A voltage distribution will exist along the lines, zero being located at the first grounded point encountered. Any part of the coolant line which is electrically conducting and not directly grounded may develop a hazardous voltage.
To prevent the above scenario, directly ground all metal plumbing components in both flow and return coolant lines attached to the EIK, see Figure 2. Steps must be taken to prevent contact with all electrically conducting materials. For further information please contact your CPI representative.
Do not attempt to operate the EIK until it has been determined that all precautions have been taken to protect personnel from all hazards.
Microwave Radiation
WARNING:
PRECAUTIONS SHOULD BE TAKEN TO PREVENT EXPOSURE OF PERSONNEL TO THE MICROWAVE FIELDS PRODUCED BY THE EIK. EIK MILLIMETRE WAVE WAVEGUIDE CIRCUITS EMPLOY HIGH POWER DENSITY RF WHICH MAY RADIATE FROM ANY WAVEGUIDE FLANGE GAPS.
Equipment
Current Limiting
While every effort has been made to ensure adequate electrode spacings within the EIO, occasional electrical breakdowns are possible. Many power supplies use large capacitors for filtering purposes which provide sufficient current, when a breakdown occurs, to damage the EIO beyond repair. It is strongly recommended that the EIO current be limited by inserting a resistor (typically, 1000 Ohms) in a series with the high voltage power supplies unless a peak current from the power supplies is limited in some other way.
NOTE:
The 1kΩ resistor in the collector leads shown in Figures 1 & 2 is not primarily for arc protection, but is to ensure that the collector is always somewhat negative with respect to the EIO body.
Heater Voltage
The EIO cathode heater filament has one terminal internally tied to the cathode electrode; therefore, the heater power supply must be floated (high voltage isolated) at cathode voltage. If a DC heater supply is used, apply negative heater voltage to the heater lead (yellow lead) and positive heater voltage to the cathode lead (white lead).
Anode
The anode provides a means of controlling the output power by controlling the cathode current of the EIO; whilst the cathode voltage remains constant. The anode voltage is applied between the anode and cathode.
NOTE:
Anode current may flow in the reverse direction through the anode power supply. The design of the anode power supply must take this factor into consideration.
Collector
The collector is insulated from the EIO body to allow for body current monitoring and for the collector potential to be depressed with respect to the body potential. It should be biased negatively with respect to the body by about a minimum of 100 volts, the actual value is not critical but prolonged operation at zero bias could reduce EIO life.
Interlock System
CAUTION:
INTERLOCKS SHOULD BE BUILT INTO THE SYSTEM TO REMOVE OR PREVENT THE APPLICATION OF CATHODE AND ANODE VOLTAGE IS ANY OF THE ABSOLUTE RATING OF THE EIO ARE EXCEEDED. INSTALL COOLANT FLOW INTERLOCKS ON THE COOLANT EXHAUST SIDE OF THE EIO.
High Voltage Cables
The high voltage insulation used on the EIO wires is easily damaged by contact with sharp edges, abrasive material, or by forcing the wires into tight bends. Preserving the integrity of the insulation is essential in order to prevent high voltage arcing.
WARNING:
ANY MINUTE DAMAGE TO THE HIGH VOLTAGE WIRE INSULATION COULD POSE A LETHAL HAZARD. IT IS RECOMMENDED THAT THE WIRING BE ENCLOSED IN A PROTECTIVE SHIELD TO PREVENT PERSONNEL FROM COMING INTO ACCIDENTAL CONTACT.