Mitel SX-200 Documentation page 477

SECTION 9105/9110-096-l 80-NA
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Page 38
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-10 volts 5 %.
When these voltages are within tolerance, a signal is sent to the
AC/DC converter which turns on the 48 Vdc regulator. The regulator
provides split DC outputs of -48 volts (-48 Vl) and -48 volts (-48 V2).
8.37 A backup DC power source of between 42 to 56 Vdc may be
connected to the SX-100 power supply. This voltage is also
sensed by the out-of-tolerance circuit and will activate the 48 Vdc
regulator. Out-of-tolerance voltages will turn off the regulator under
power failure conditions.
8.38 An out-of-tolerance (OOT) circuit constantly monitors all volt-
age levels and should a deviation occur, the power fail transfer
circuits are activated.
8.39 The ringing generator uses the -48 V2 output to derive a 90
Vrms 20 Hz supply for use within the system for ringing and
message waiting purposes. A fused output is available to provide
ringing for night bells.
Power Supply, SX-200
8.40 The SX-200 power supply is housed in a metal cabinet which
forms the lower rear door of the SX-200 cabinet. It is a fully
switching
sections:
AC/DC Converter
Preregulator
DC/DC Converter
Ringing Generator
Out-of-Tolerance
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8.41 The AC/DC converter is designed to operate with an input of
either 115 Vat 60 Hz or with an adapter for 230 Vat 60 Hz to
produce an output of 60-64 Vdc which is supplied as an input to the
DC/DC converter through a bridge rectifier.
8.42 Because the AC/DC converter has a minimum input capacitance
of 0.08 Farad, a somewhat high current flow could be expected
on power-up. Therefore a preregulator is placed ahead of the capaci-
tors to slow down this charging process. The preregulator then main-
tains the basic DC level to between 60 and 64 Vdc.
8.43 The -64 Vdc volts is fed to the main DC/DC converter and to a
control voltage supply. The DC/DC converter may also be fed
by a 48 Vdc battery. Since the DC level from the bridge rectifier is
greater than -48 Vdc volts when AC is applied (-60 V to -64 V), the
battery supply may be connected permanently to allow instantaneous
cut-in should the AC power fail. The control voltage supply generates
a number of levels which are used to operate the main converter. The ,&@
main converter produces the following DC voltages required by the t.
SX-200 system:
power supply comprising
Detector.
the following basic