Operation; Theory And Circuit Analysis - GE 4PE21A1 Instructions Manual

POWER SUPPLY
EBI-3527B
used, turn
the CENTERING VOLTAGE ADJ
control (Rl)
full
counterclockwise.
The
Power
Supply
may
be
grounded at
a
remote
point
by
removing the wire at
V4
-G2
to
ground, and connecting the
re-
mote ground wire
to
P1-8.
OPERATION
Apply
power to the unit by turning the
circuit breaker
to ON.
This
energizes
the
time delay relay, Kl,
which
cycles for
about
30
seconds before actuating
relay
K2,
thus allowing sufficient time for
the
filament
to
heat before plate power is ap-
plied.
K2
is
a d
-c relay operating
on
volt-
age supplied
from
the
rectifier,
V5B. With
S2
set at Eo,
adjust the voltage
control,
R38,
marked
Eo
ADJ, to
obtain
the
desired oper-
ating voltage, as indicated
on the
Plug -In
Meter,
Type TX
-15-A*.
E0
should not
nor-
mally require readjustment for
a
given
voltage
unless
the Type
5651
tube is changed.
To
read
current, set
the
selector switch,
S2, to
I.
The
settings Il through
I4
read
the
regulator
tube
(V1
through
V4)
cathode
currents,
which should balance within
10%.
With
short power line
failures
of about
five
seconds
or less, relay
Kl will not
re-
cycle
and
B+
power
will
return
immediately.
For longer failure intervals,
Kl will
re-
cycle but will not
require
the full
relay
time
to
pick
up
again. This is
true because
of
its thermal time delay operating principle.
THEORY AND
CIRCUIT ANALYSIS
The
Power
Supply, Model 4TP23A1,
is
an
electronically regulated
d
-c
supply with
a
nominal output voltage of
280
volts
and
a
maximum
current
of
1600
ma.
The
Power
Supply
provides
a
steady power source in-
dependent
of
fluctuations
in
input voltage
or
load
variations
within the
specified
limits.
The input
circuit uses
a
germanium
recti-
fier
stack
in a
bridge
rectifier
configuration.
This, together
with the choke
-input
filter
L1
-C1 through
C5,
provides
the
highest
utilization factor
of
T1
and
allows the use
of a
smaller transformer.
This supply
uses
electrolytic capacitors
in the
filter circuit
to
reduce size
and
weight.
It
should be noted
that
the
normal life expectancy of
these
capacitors
at
55
C
(131
F)
is
five
years or
more.
At
25 C
(77
F) the
figure is
15
years.
The
supply
uses open
-frame transformers
with Class
B
insulation, which allows con-
siderable saving
in
size and weight.
It
is
perfectly normal for these
transformers
to
run hotter than the older Class
A
units.
The
series regulator section is conven-
tional, using four
dual
triode
series -parallel -
connected
regulator tubes,
Type 6336. The
*Required
accessory
equipment.
d
-c
output voltage is dependent
almost en-
tirely
on
the voltage
reference
and the
ratio
of
the dividing
resistors,
R35
through
R38.
A
Type 5651
tube
is used as the
reference
and 1.0%
resistors
are
used
in the
dividing
network.
V6B
is the
first
d
-c amplifier,
cathode coupled via
V6A
into
V5A
to
obtain
the
proper polarity
of
feedback voltage.
The
action
of the
regulator circuit
is
best
explained
by
considering
the
effect
of
a
variation
of
the output load.
An
increase
in
load
current
tends
to
decrease
the
out-
put voltage because of
greater
drop
across
the Type
6336
regulators.
A
sampling
of
the output voltage
appears across
the
divider
network at
the
grid
of V6B,
which
operated
at
75
to 85
volts positive,
or several volts
more negative than the plate of the voltage
reference
tube,
V7,
normally
about
85
volts
positive.
The
decreased voltage at the grid
of
V6B
causes it
to
become more negative,
decreasing its
plate
current.
The
grid volt-
age at
V6B
is
thereby increased, causing
the cathodes
of
V6A
and
V5A
and the
plate
of
V5A
to
go
more positive, resulting
in
a
plate
resistance
drop
across
V1
-V4, which
returns
the output voltage to
normal.
The
amount that it will deviate from normal is
a
function of the
gain of the
d
-c amplifier.
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