SAFETY
Digital On/Off control of 24V supply to each PSU, provides removal
of the ‘source of energy’.
In the default mode, if the USB connection powers down, or is unplugged,
then the high voltage enable bus control line goes low and the high
voltage supplies are turned off. This can disabled by moving a link
in the USB receiver box. It is the responsibility of the user to
ensure the safety and integrity of the resulting system. If the
high voltage enable is forced low externally by an open collector
transistor, then the high voltage supplies are turned off.
The optical link sends idle packets so if these packets are not
seen for 2 frames, then the high voltage enable is turned off, and
all isolated supplies will be turned off.
WIRING
Pin 1, & 2 & 9 = +24V supply to all PSUs
Pin 5, 7, & 8 = 0V supply to all PSUs.
All connections must be daisy-chained to all connectors.
Notes
1/ The PSUs connect 0V to their chassis and to their HV o/p cable
braid, however the 24Vdc supply should not rely on either of these
paths for the power connection.
2/ Each PSU can draw up to 1 amp, so with multiple PSUs connected
to a single ribbon cable, additional power connections will need
to be made to the ribbon to distribute the power. The maximum current
the ribbon cable can take is 1 amp per connection. (An HP Series
PSU drawing no load current will take approx 300mA)
SPECIFICATION
Input voltage: 24Vdc ± 10% at 1 amp per
PSU (USB Receiver is powered by USB connection)
Resolution: 16bit monotonic Voltage Control, 8
bit Voltage Readback, 12 bit Current Readback.
Temperature Coefficient: 5ppm/°C
Cleaning: Use a lint free cloth soaked with isopropyl
alcohol, ensuring the unit is completely dry before use.
Environmental Conditions:
Indoor use only
Operating Temperature 0°C to +50°C
Altitude up to 2000m
Storage Temperature -35°C to +85°C
Maximum relative humidity 80% for temperatures up to 31ºC,
decreasing linearly to 50% relative humidity at 40º C.
The unit is to be supplied from a current limited supply providing
24Vdc, impulse limited to (overvoltage) Category I of IEC60364-4-443.
For use in an environment of pollution degree 2
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.
If an electrical test is to be carried out prior to fitting the
power supply, it is essential that the person undertaking this work
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 24V SUPPLY, IS CONNECTED.
AFTER DISCONNECTION FROM THE SUPPLY, ALLOW 30 SECONDS BEFORE HANDLING
SO THAT ALL THE CAPACITORS CAN DISCHARGE. ALSO ENSURE THAT THE POWER
INPUT TO THE BIASING SUPPLY IS REMOVED AND THIS SUPPLY ALSO IS FULLY
DISCHARGED. 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
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 : latest : Clause 6.5.1. The case of the units
must 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 connections 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 o/p current of the biasing supply, providing the floating
voltage must be limited to 10mA.
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 (ground) conductor must not contain any
switches or fuses.
Under worst case conditions the unit draws a current of 1A 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 50°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.
3/ Option Codes PR & PL POWER SUPPLIES ARE DISPATCHED WITH INTERNAL
POTENTIOMETER SET TO MAXIMUM. TURN DOWN TO ZERO BEFORE CONNECTING
TO 24 VOLT SUPPLY.
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