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.
If an electrical test is to be carried out prior to fitting the power supply,
it is essential that the person undertaking this work be a qualified electronics
technician who is fully aware of the particular dangers associated with high
voltage switch mode power supplies. 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 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 : 1993 : 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. The unit is intended to be installed in an electrical enclosure and 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.
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 1A (+24V ) and 25mA
(-15V) 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 output is 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 will operate in any orientation,
however it is not recommended to operate with the side fitted with the
silk-screen as the lowest face.
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.
