Dranetz Energy Platform User Manual page 98

Nominal Values, continued
Frequency
synchronization
Frequency
tracking
5-16
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Normal frequency synchronization (sync) of the Energy Platform analog signal
processing circuits is controlled by analyzing the external AC voltage signal input on
channel A. If sync is lost, then internal sync is automatically selected. The frequency
used for internal is entered under Frequency on the Nominal Values screen (see page 5-
14).
Typically, external sync on Ch D is specified if it is known that signal on A is
inappropriate for use as a sync source (i.e. the frequency is unstable or DC). A low
distortion 50, 60 or 400 Hz signal can be input to Ch D and used as a sync signal.
NOTE: Failure to connect an external sync or to select an internal sync during current
monitoring will result in erroneous data being collected and displayed.
Tracking determines how the phase locked loop circuitry responds to sudden changes
in frequency.
Standard mode: On a normal power quality application [Standard], the system is
designed to "ride through" voltage changes to keep tracking the fundamental frequency
even in the absence of voltage.
Fast mode: When operating on a local generator [Fast], the frequency will vary more as
loading changes occur. The Fast mode allows the instrument to follow these changes
more closely.
Internal mode: In cases where no reference signal is available (such as DC monitoring),
the Internal setting is used to set the sample rate.
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