Global Specialties 1522 - Manual User Manual

Page 8

PCB Components

767E/01 PCB REV-01 contd...

=======================================================================

Ref Designator

Value

=======================================================================

RESISTORS

R36

200K(390K),1/4W,0.1%,MFR

R37

10M(20M),1/4W,0.1%,MFR

R38

10M(20M),1/4W,0.1%,MFR

R39

200K(390K),1/4W,0.1%,MFR

R40

100K,1/4W,5%,MFR

R41

100K,1/4W,5%,MFR

R42

11K,1/4W,5%,MFR(SEL-W)

PRESETS

PR5

1K,VER, M/T BOURNS (3296-W)

PR6

10K, VER, M/T BOURNS (3296-W)

PR7

10K, VER, M/T BOURNS (3296-W)

PR9

2K,VER, M/T BOURNS (3296-W)

PR10

2K,VER, M/T BOURNS (3296-W)

PR11

10K, VER, M/T BOURNS (3296-W)

PR12

10K, VER, M/T BOURNS (3296-W)

PR13

10K, VER, M/T BOURNS (3296-W)

PR14

10K, VER, M/T BOURNS (3296-W)

PR15

2K, VER, M/T BOURNS (3296-W)

CAPACITORS

NOT USED

10uF,35V,EL,RAD

47uF,50V,EL,RAD

10uF,35V,EL,RAD

SECTION - 4

CIRCUIT DESCRIPTION

The Model 1522 Digital Wattmeter measures true rms

values of voltage across the load, the load current and
the power consumed by the load (real power in Watts ).

Main PCB (ref: WD 76XX-01)

The line voltage is sensed at the "VIN H" and "VIN L"

terminals. It is attenuated by a factor of approx.50 and
connected to the inputs of IC16 (TL071). The circuit
associated with IC16 converts the "floating" signal to a
"single-ended" signal. The waveform on test point TPV1
is a scaled version of the line input voltage. This signal
is connected to IC14 (AD736), which is a RMS - DC
converter. The output at pin 6 of IC14 is a DC voltage
proportional to the input line voltage. Attenuator network
R31, PR10 (VCAL), and R33 is used to attenuate this DC
voltage by a factor of approximately 2. The DC voltage on
TPV2 should be exactly 1/100th the RMS value of the
input line voltage.

The load current is sensed by a "shunt" resistor, R16,

in the neutral return path. The voltage across R16 is
connected to the inputs of IC9 (TL071). The circuit
associated with IC9 converts the "floating" signal to a
"single-ended" signal. The waveform on test point TPI1
is a scaled version of the load current. This signal is
connected to IC12 (AD736), which is a RMS - DC
converter. The output at pin 6 of IC12 is a DC voltage
proportional to the input load current. The resistor
network R30, PR9 (ICAL), and R28 is used to amplify this
DC voltage by a factor of approximately 4.0. The DC
voltage on TPI2 should be adjusted to 200mV for a load
current of 10 A. IC15 (AD633) is an analog multiplier.
Signals from TPV1 (corresponding to the line voltage) and
TPI1 (corresponding to the load current) are connected
to input pins 4 and 2 resp. of IC15. The output on pin
7 corresponds to waveform of the instantaneous power
consumed by the load.