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GENERAL
On receipt the unit should be carefully unpacked and inspected
to ensure that no transit damage has occurred. Provided that this
inspection is satisfactory and reveals no evidence of damage then
installation can proceed.
It is essential that the person undertaking the installation and
set-up of this power supply has received appropriate technical training
to be aware of the hazards to which that person may be exposed in
performing the tests, and of measures to minimise the risks to themselves,
and other personnel. Metallic or conductive tools should not be
used to adjust any of the potentiometers. The unit has no user serviceable
parts and should not be dismantled.
DO NOT HANDLE OR TOUCH THESE UNITS WHEN THE SUPPLY IS CONNECTED.
AFTER DISCONNECTION FROM THE SUPPLY, ALLOW 30 SECONDS BEFORE HANDLING
SO THAT ALL THE CAPACITORS CAN DISCHARGE. To ensure that the output
is fully discharged short to ground before touching any high voltage
circuit.
Care should be taken not to operate the unit outside the specified
limits given above, failure to do so may damage the unit.
COMPLIANCE WITH SAFETY STANDARDS
The unit is designed to meet Normalised European Safety Standards
for installation in equipment conforming to EN61010 and hence installation
of the power supply unit into the equipment should comply with the
following requirements.
a. A PROTECTIVE EARTH must be provided for safety in accordance
with EN61010 Part 1 : Clause 6.5.1. The case of the units should
be bonded to this protective earth.
b. The output is classed as hazardous and must therefore not be
accessible to operators. The output must be isolated from accessible
circuits by Double Insulation or a protective screen as defined
in EN61010-1.
c. It is intended to be installed in an electrical enclosure and
the unit and its input connector should not be accessible to the
operator. Access should be restricted to authorised service personnel
only, with use of a tool. Care should be taken to prevent access
to the interior of the unit and protect against items (e.g. tools
or wires) inadvertently entering the interior of the unit.
d. The unit is not fitted with a fuse and so should be operated
from a limited supply of <8 amp.
e. The primary safety interlock must remove the 24Vdc supply, thereby
removing the source of energy, NOT relying on the Inhibit input.
INSTALLATION
The outputs of these units are considered hazardous and should
be installed such that they cannot become accessible. The output
should be connected such that the shortest creepage and clearance
path is to a protective earth connection. ENSURE that a LOW IMPEDANCE
connection is made to the unit chassis from the system PROTECTIVE
EARTH. The safety earth conductor must not contain any switches
or fuses.
Under worst case conditions the unit draws a current of 7A and
any input supply cable must be of a suitable type and rating. The
unit is not fitted with a fuse and so should be operated from a
limited supply. Fuses may be fitted externally to the unit to protect
unit and interconnecting wiring etc. but these should be rated to
prevent nuisance failures. Care should be taken in the design of
the interconnecting wiring within the system to ensure that connectors
with hazardous voltages cannot be connected to accessible circuits.
Ensure that the filaments outputs are connected to the load prior
to operation of the unit and that a good low impedance high voltage
joint is made. Sharp points on either the high voltage or return
joint should be avoided as this will cause corona which will make
the output appear noisy. In general a tracking distance (creepage
distance) of 25mm (1 inch), per 10kV to earth is advised as a minimum
to ensure no breakdown or corona occurs, a much greater distance
will be required under adverse conditions. Care must be taken not
to damage the cable inner when forming the connections.
During arcing currents exceeding 1000 Amps will flow. It is important
that these currents return to the high voltage power supply by the
shortest possible route using the screen (shield) of the output
cable. Failure to observe this will result in the control terminals
of the unit seeing large voltage spikes during arcing and radiation
of electromagnetic interference.
Adequate ventilation should be provided to keep the unit cool and
the ventilation inlets should not be covered in any way. The ambient
air temperature around the inlet must not exceed 45 °C. The
unit is fitted with a thermal cut-out to protect itself should the
ambient temperature exceed this level. To restart the unit it must
be allowed to cool. De-asserting and re-asserting the INH input
will then clear the trip. The unit will operate in any orientation,
however it is not recommended to operate with the silk-screened
face as the lowest face.
OPERATING INSTRUCTIONS
1/ Installation should only be undertaken by personnel qualified
in high voltages and who are familiar with high voltage safety regulations.
2/ Connect tube, 24 volt power input & control inputs (either
computer, external potentiometer or link for the use of the internal
potentiometers).
3/ After setting control potentiometer or control voltage to zero
& heater maximum to 50%, turn on power supply.
4/ Using the monitor voltages to check the power supply output,
increase the output voltage until 10 kV or a safe level is reached.
5/ Increase beam current until required beam current is reached
(increasing filament maximum if necessary).
6/ Set filament maximum potentiometer to limit the filament current
to the required level.
7/ Set output voltage & beam current to required values.
8/ Over current or over temperature trip are reset by the on/off
control.
OPERATING NOTES
1/ HIGH VOLTAGES ARE DANGEROUS. ENSURE THE OUTPUT IS FULLY DISCHARGED
BY SHORTING TO GROUND BEFORE TOUCHING ANY HIGH VOLTAGE CIRCUIT.
2/ The unit is short circuit proof but care should be taken that
the high voltage cannot be shorted into one of the control pin connections.
3/ TO ENABLE THE UNIT PIN8 MUST BE TAKEN TO LESS THAN 1.5V WITH RESPECT TO PIN9.
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