HP 3457A Service Manual page 49

Operation
3-27. Range Selection. The Auto-Range feature automatically selects the appropriate range for the current
being measured. The Auto-Range feature can be disabled by selecting Manila1 Ranging. There are
5
DC
current ranges available; 300 LIA, 3 mA, 30 mA, 300 mA and 1 A. There are 3 AC current ranges available;
30 mA, 300 mA and 1 A. The maximum input current for DC or AC inputs is 1.5
A
peak. The d e f a ~ ~ l t range
is Auto-Range.
T o select Manual Ranging and maintain the present range
-
Press the Blue SHIFT key then the
&/HOLD
scroll key.
T o select Manila1 Ranging and the next higher range
-
Press the ?/AUTO scroll hey.
T o select Manual Ranging and the next lower range
-
Press the
HOLD
scroll hey.
T o return t o Auto-Ranging
-
Press the Blue SHIFT hey then the ?/AUTO scroll key.
3-28.
Measurement Resolution. Measurement Resolution is changed by selecting the n ~ ~ n ~ b e r
of digits dis-
played. YOLI can choose a display of 3 1/2, 4 1/2, 5 1/2 or 6 1/2 digits. The 1/2 digit refers t o the most sig-
nificant digit which is limited to a value of 0, 1, 2, or 3. The default number 01' digits displayed is 5 1/2
(most significant digit plus
5
digits).
T o change the n~umber of digits displayed
-
Press the DIGITS DlSP
I
P conrigusation key, enter the
number 3,4,
5
or
6
and press the ENT
/
LAST ENTRY key.
3-29. Integration Time. The Integration time can be changed to reduce measurement noise or t o permit
faster readings. The integration time is dependent upon the power line frequency and is expressed in num-
ber of power line cycles (NPLC). There are six integration times available; 100 PLC, 10 PLC, I PLC, .I PLC,
.005 PLC and .0005 PLC. The greater the PLC number, the quieter and more accurate the reading will be
and the slower the measurement speed.
T o select the Integration Time
-
Press the NPLC
/
A configuration key. Use the
TI A UTO
or
HOLD
scroll key t o display the desired number and press the ENT
/
LAST ENTRY key.
The Integration Time cart also be changed
1)s
pressing the NPLCIA k e y , entering the desired ~turnbcr directly using the
AIA1'H keys and pressing the ENTILAST ENTRY key.
3-30, lnput Connections. For current measurements, the input current is applied to the INPUT
1
and L O
Terminals. This applies to both Front and Rear Terminal operation. When using the
HP 44491A Plug-111 as-
sembly, the input is connected t o the
1
and LO inputs of either channel 8 or channel 9.
3-31. FrontlRear lnput Selection. The Inpi~t configi~rations are Front Terminals, Rear Terminals/Scanner
or Open. Only one input configuration (front, rear, scanner or open) can be selected at a time.
T o select Input configuration
-
Press the TERM
/
M configuration key. Use the
TI A UTO
or &/HOLD
scroll key t o display the desired input and press the ENT
/
LAST ENTRY key.
The input cun ulso be c~hurtged by prettirtg thv
TERM/M
k e y , errti~ring thr uppropriute rtrcrnl~rr rcting thu M A T H kuys itnd
pressing the ENTILAST ENTRY k e y .