Section 3 - Theory Of Operation; Block Diagram Description - Tektronix 067-0883-99 Instruction Manual

UNIVERSAL LOAD UNIT
SECTION
3
THEORY OF OPERATION
Block Diagram Description
A simplified block diagram of the Universal Load Unit is shown in
Fig. 3-1. The diagram illustrates as typical one of the twelve active cells
connected to ULU controls and indicators.
When the output from a power supply under test has been connected to·
the rear panel connectors P1, P2 and P3, continuity can be established
between its output and one or more of the active cells within the ULU via
the CHANNEL SELECT switch. This thirteen position wafer switch connects
ULU controls and output monitoring circuits to each of the twelve active
cells. The thirteenth switch position connects one or two user selected,
fixed resistors between ground and the power supply under test.
The active channels are divided into six groups of two by polarity
and current handling capability as shown in Table 3-1. All cells are ground
referenced.
Table 3-1
Maximum Maximum Maximum
Channel Voltage Current Power Polarity
1 ' 2 50
v
24 A 120 W*
+
3, 4 100
v
10 A 80 W*
+
5, 6 150
v
2 A 80 W*
+
7, 8
50
v
24 A 120 W*
-
9, 10 100
v
10 A
Bo
W*
-
11 ' 12 150
v
2 A 80 W*
-
13 350
v
10
w
+
*
or 500 watts total input power, all channels
3-1