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The PT Interface board is a Low Pass filter signal conditioner that
converts the input voltage from the Potential Transformers (PT) to a 24 volt
pulse that can be routed to Woodward digital speed sensor equipment or PLC
based frequency counting equipment. The interface provides 3500 Volt
isolation between the PT input and pulsed output.
A built in 3-pole Butterworth filter blocks high frequency noise preventing
erroneous readings from reaching the frequency counting equipment.
The device is very sensitive and can detect AC voltages as low as 0.2 VAC.
The amplitude of the output pulse is independent of the input voltage. The
nominal frequency range is 6 HZ to 120 HZ.
The ability to sense low AC voltage coupled with a broad frequency range
allows governors to use the PT signal as a reliable primary speed signal.
Due to residual magnetism, the generator excitation does not have to be
active to gain a valid speed signal.
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