HP 6177B Operating And Service Manual page 27

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5-29 PROGRAMMING SPEED
Definition: The time (flsecs) required
for the output current to change from
zero amps to within "X" milliamps of
the maximum rated output, 0:- from
maximum rated output to within "X"
milliamps of zero, "X" is genera 11y
of the same order as the load regula-
tion specification.
5-30 To check the constant current remote pro-
gramming speec., proceed as follows:
a. Connect test setup shown in Figure 5-7.
b. Turn VOLTAGE control fully clockwise.
c. Set meter switch to AMPS and range
switch to highest current range.
d. Adjust CURRENT control until front pane 1
meter indicates exactly the maximum rated output
current.
e. Close line switch for mercury wetted
re lay and observe waveform on oscilloscope. Rise
time indicates up-programming speed and decay
time indicates down-programming speed.
£.
The programming speed should be within
the tolerances of Figure 5-8. Output should go
from zero to 99 Volts (Model 6177B) or from zero to
49.5 Volts (Model 6181B). Fall time (down pro':
gramming) should be almost identical to the rise
time shown on Figure 5-8 except for inversion.
OSCILLOSCOPE
POWER SUPPLY
<§140A
UNDER TEST
- .;.- G
/ -
'i'J'
AO
AI A2
+ - /
I
REAR
Q
Q
~
TERMS.I(
I
R51
~I
1- -,
RLI
LINE! I :
),1
RESISTANCE
MODEL NO.. (OHMS)
SWITCH
I I
I
I
RSI
I
RLI
-r-,if~
I
61778
I
2
I
98
i
I
I
n
--L..-
u
I
I
I
390
115VAC
I
MERCURY
61818 10
60Hz
I
WETTED
I
RELAY
L.::'~E ~.J
~
NOTES:
L OSCILLOSCOPE SHOULD BE DC COUPLED.
2.MERCURY RELkY (CLARE TYPE HGP 1002 OR W.E. 276B)
CAN BE USED TO PROGRAM THE SUPPLY, A TRANSISTOR
SWITCHING NETWORK CAN ALSO BE USED" PARTICULARLY
IF
60Hz LEAKAGE MAKES WAVEFORM DIFFICULT TO
OBSERVE.
Figure: 5-7. Programming Speed, Test Setup
5-7
100%r---- - - -
, I
I
!
'OUT
I
o
100 200 300
400
500
t u . $ E C -
Figure 5-8. Up-Programming Speed Vvaveform
5-31 OUTPUT STABIIlTY
Definition: The change in output
CUr-
rent for the first 8 hours follOWing a
30 minute warm-up period. During
the interval of measurement all param-
eters such as load resistance, ambient
temperature, and input line voltage are
he 1d constant.
5-32 The stability of the supply in constant cur-
rent operation must be measured while holding the
temper..ature of the power supply and the external
current sampling resistor (RS) as constant as pos-
sible. A thermometer should be placed near the
supply to verify that the ambient temperature re-
mains constant during the measurement period.
The supply should be located away from stray air
currents; if possible, in an oven which is held at
a constant temperature. Variations of the voltage
across the current sampling resistor over the spec-
ified 8 hour interval are measured on the digital or
differential voltmeter and may be recorded on a
strip chart recorder. Since such voltage measure-
ments are generally being made at a rather low
leve 1,
it
is important to check that the stability of
the measuring instruments is adequate to insure an
accurate check. on the power supply periormance.
5-33 To check the output stability, proceed as
follows:
a. Connect test setup shown in Figure 5-3.
b. Turn VOLTAGE control fully clqckwise.
c. Set range switches to desired current
range and
+
lead of differential voltmeter to appli-
cable sampling resistor (RS1, RS2 or RS3).
d. Set METER switch to AMPS and adjust
CURRENT control to obtain rated output current.
e. Allow one hour warm-up then record dif-
ferential voltmeter indication.
f.
After 8 hours. differential voltmeter
reading should not change by more than 125f-LVdc