DF3/FF3 MANUAL
18
118018-001
Rev E
4
PRINCIPLES OF OPERATION
he DF3/FF3 series of high voltage power
supplies utilize sophisticated power
conversion technology. A variety of analog,
digital and power conversion techniques are used
throughout. The intention of the Principles of
Operation is to introduce the basic function
blocks that comprise the DF3/FF3 power supply.
For details on a specific circuit, consult
Spellman’s Engineering Department.
See Table 4.1 for a list of the main assemblies
found in a typical DF3/FF3 power supply.
The DF3/FF3 power supply is basically an AC to
DC power converter. Within the power supply,
conversions of AC to DC, then to high frequency
AC, then to high voltage DC take place. By
reviewing further the sub-assemblies, a basic
understanding of the process can be gained.
4.1
CHASSIS
The DF3/FF3 is a compact, high efficiency, high
voltage power supply. The power supply can
supply three kilowatts of DC power as well as a
regulated filament output.
WARNING
:
The energy levels used and
generated by the power supply can
be lethal! Do not attempt to operate
the power supply unless the user has
a sufficient knowledge of the dangers
and hazards of working with high
voltage. Do not attempt to approach
or touch any internal or external
circuits or components that are
connected or have been connected to
the power supply. Be certain to
discharge any stored energy that
may be present before and after the
power supply is used. Consult IEEE
recommended practices for safety in
high voltage testing #510-1983.
4.2
LINE RECTIFICATION
AND FILTERING
Basic AC line rectification provides the DC
voltage for the high frequency inverter and the
filament supply.
The FILTER CAP. ASSEMBLY and main
chassis components comprise the circuits for line
voltage rectification. The line input voltage can
vary from 180 up to 242 volts within the
DF3/FF3 series. In general, the following
variations can be ordered.
200Vac
10%, 50/60Hz, 400Hz, three phase or
single phase.
/-10%, 50/60Hz, 400Hz, three phase or
single phase.
/-10%, 50/60Hz, 400 Hz, three phase
or single phase.
400Hz exceed leakage current limits.
Other input voltages can be accommodated. If
the user is unsure of which input voltage option
is supplied, check the serial tag on the rear of the
power supply or consult Spellman Sales
Department.
Circuit protection is provided by CB1 (SYSTEM
BLOCK DIAGRAM CHASSIS DF3/FF3
SCHEMATIC). CB1 is a fast acting circuit
breaker. The line input is connected directly to
the line side of the CB1. The load side is
connected to K1. K1 is a definite purpose
contactor. K1 provides fail safe type
disconnection of the line voltage to power supply
rectification circuits. K1 coil is controlled by
variety of circuit conditions, which will be
described later on. The load side of CB1 is also
connected to the low voltage power supply. The
LVPS su5V, ±15V and +24V dc to the
control electronics.
WARNING
Line voltage is present whenever the
power supply is connected to
external line voltages. Be sure to
disconnect the line cord before
opening the unit. Allow 5 minutes for
internal capacitance to discharge
before removing any cover
.
T
