Operation - Data General NOVA 4/S Manual

Data General Corporation (DGC) has prepared this manual for use by DGC personnel and customers as a guide to the proper installation, operation, and
maintenance of DGC equipment and soft ware. The drawings and specifications contained herein are the property of DGC and shall neither be reproduced in whole or
in part without DGC's prior written approval nor be implied to grant any license to make, use, or sell equipment manufactured in accordance herewith.
OPERATION
Off-Line Switching Regulator
The ac line voltage passes through a line filter to the
VNR source where it is converted into a high dc
voltage source. Although this de voltage source varies
from 259 VNR to 337 VNR with the line voltage, it is
referred to as 300 VNR.
For 100/120 volt operation, the 300 VNR source rectifies
and doubles the ac line source by connecting the
junction of Cl and C2 (J1-9) to the neutral side of the
line (J1-8) to provide a 300 VNR ac source; for 220/240
operation, it simply rectifies the ac line source.
The pulse width modulation control governs the
operation of the inverter, and, in turn, of the dc
regulator, by controlling the amount of power through
the inverter. It opens and closes the power path once
every 50 us (at a 20 KHz rate) and varies the ratio
between the open time and the closed time (the duty
cycle) in accordance with the variation on the +5V output.
As the line voltage decreases or the +5V output load
increases, the pulse width modulation control increases the
closed time to transfer more power. In this way, the pulse
width modulation control regulates the +5V output of the
dc regulator.
Inverter
The inverter receives power from the 300 VNR source
and transforms it into the ac voltage outputs which
power the dc_ regulator. Its main component is
transformer Tl. Tl operates at 20 KHz with a variable
duty cycle. Its maximum duty cycle is just less than 50
The de regulator receives ac voltages from the inverter
and converts them into five different low dc voltage
outputs: +95V, +12V, +15V, -5V, and -11V. It
consists of rectifiers, an inductor Ll, various filter
circuits, and two voltage regulators.
The +5V output feeds back to the pulse width
modulation control to regulate the duty cycle of the
inverter, which, in turn, regulates all the outputs of the
de regulator.
The +12V output passes through a simple series pass
regulator to produce a very well regulated +12V
The +15V output is derived from Tl and the +5V
in the de regulator. It has no additional regulation.
Since the pulse width modulation control removes all
however, their effect is relatively small.
The -5V and -11V receive additional regulation. The
-OV output is regulated by a +5V three terminal
regulator with its positive output grounded. The -11V
output is regulated by a -12V three terminal regulator.
also produces +5V AUX. These voltages power most of
references.
when the system is powered up. Its main component is
a capacitor with a large time constant. This capacitor
must charge up before the pulse width modulation
the faults which shut down the pulse width modulation
voltages to come up slowly when the fault is removed.
Various circuits monitor the operation of the power
over current conditions.
Under Voltage Detection
The under voltage detector continually monitors the +5V,
-OV, +12V and the +15V outputs. When any of these
outputs falls below the minimum operating level (see
Voltage Current
Output Min Max Min Max
+5V +4.95V +5.2V 5A 35A
+12V +11.7V +12.7V 0 5A*
+15V +14.0V +16.0V 0 5A*
-5V -4.75V -5.25V 0 1.5A
-11V -11.0V -12.5V 0 0.0254
+12 MEM +11.3V +12.7V 0 3.0A*
-5 MEM -4.75V -5.25V 0 0.05A
MEM lines must NOT exceed 5 Amps. When battery backup is operating,
+12 MEM draws a maximum current of 0.3A.