Fluke 434 - Manual (Page 50)

Fluke 433/434
Users Manual
11-4
PREFerences. With the demand interval set to OFF the Trend functions as usual with
automatic horizontal scaling.
Available function keys:
F1 Assign up/down arrow keys to select a row from the table
for Trend display. The selected row is displayed in the
screen header.
F2 Cursor on/off.
F3 Assign the arrow keys to Cursor or Zoom operation.
F4 Return to table screen.
F5 Switch between HOLD and RUN of screen update.
Switching from HOLD to RUN invokes a menu to select
immediate (NOW) or TIMED start time which allows you
to define start and duration of the measurement.
Cursor. When the Cursor is on, the Trend values at the Cursor are displayed in the screen
header. Moving the Cursor off the left or right side of the screen brings the next of six
screens into the viewing area.
Zoom. Allows you to expand or shrink the display vertically or horizontally to view
details or to fit a complete graph within the screen area. Zoom and Cursor are operated by
the arrow keys and explained in Chapter 17.
Offset and Span are preset for a good display in most cases. This is based upon Nominal
Voltage (Vnom) and Current range (A range). If desired, you can adjust Offset and Span.
The adjustment menu is reached via the SETUP key and function key F3 - FUNCTION
PREF. See Chapter 18, FUNCTION PREFerences.
Tips and Hints
Power mode can be used to record apparent power (kVA) of a transformer over several
hours. Look at the Trend and find out if there are times that the transformer is overloaded.
You can transfer loads to other transformers, stagger the timing of loads, or if necessary
replace the transformer with a larger one.
Interpretation of Power Factor when measured at a device:
• PF = 0 to 1: not all supplied power is consumed, a certain amount of reactive power
is present. Current leads (capacitive load) or lags (inductive load).
• PF = 1: all supplied power is consumed by the device. Voltage and current are in
phase.
• PF = -1: device generates power. Current and voltage are in phase.
• PF = -1 to 0: device is generating power. Current leads or lags.
If you see negative power or power factor readings and you are connected to a load,
check to make sure the arrows on your current clamps are pointing towards the load.
Reactive power (VAR) is most often due to inductive loads such as motors, inductors,
and transformers. Installation of correction capacitors can correct for inductive VAR’s.
Be sure to check with a qualified engineer before adding PF-correction capacitors,
especially if you measure current harmonics in your system.