3
A.C. Power
Typical circuit connections for single-
phase ac watt meters and transducers are
given in figure 5. Calibration of these types
of devices requires use of both the voltage
and current outputs of the 1040C.
Representative calibration connection
diagrams for these types of devices are given
in figure 6. The 1040C voltage output leads
are connected to the voltage terminals of the
meter or transducer, and the 1040C current
output leads are connected to the current
input terminals of the meter or transducer
(figures 6a and 6c). If the meter or
transducer uses an external current
transformer, one of the current output leads
of the 1040C should be passed through the
center of the current transformer, and then
shorted to the other lead. If the meter or
transducer uses an external potential
transformer, then likewise it must be inserted
between the 1040C voltage output leads and
the input voltage leads of the unit under test.
Refer to figures 6b and 6d for these
connections. The user should then select the
proper operating frequency, either 60 Hz or
400 Hz. The "Power" key should be pressed,
which will place the 1040C into the power
mode, enabling both the voltage and current
outputs for simultaneous operation. The
"Voltage" key should then be pressed, and
the desired voltage entered using the keypad,
followed by "V". After this, the "Current"
key should be pressed and the desired current
entered using the keypad, followed by "A".
After this is completed, pressing the
"Operate" key will enable the outputs, which
will increase to the respective values entered.
An equal sign on the front panel display
indicates that the current and voltage outputs,
and the phase angle between them, have
stabilized at the proper values. The
calibration procedure for the meter or
transducer under test can then be performed.
The power value can be varied using the
control knob or the up/down arrows, but it is
important to note that it is only the current
that changes; the voltage remains constant.
For more complete instructions on operation
of the 1040C in the ac power mode, refer to
section 2.5.6 of the operation manual.
A.C. Frequency
Calibration of ac frequency is another
procedure that requires the use of only the
1040C voltage output. The connections are
the same as for the volt meter or transducer
(Figure 2). After connection, the frequency
range (i.e. 60Hz, 400Hz) is selected, then
"Voltage" is pressed. The operator then
enters the voltage value which is appropriate
for the device under test, followed by the
voltage unit key. Fine adjustment of the
frequency can be accomplished by first
pressing the "Frequency" key, then using the
adjust knob or up/down keys to select the
value. A value for frequency can also be
entered via the keyboard, by first pressing
"Frequency", entering the value, then
pressing the "Hz" key. When the "Operate"
key is pressed, the voltage output will be
enabled and the calibration procedure for the
device under test may be performed. For
more complete instructions on frequency
operation of the 1040C, refer to section 2.5.8
of the operation manual.
