3500/25 Enhanced Keyphasor® Module

3500/25 Enhanced Keyphasor®  Module 

General Information 

The 3500/25 Enhanced Keyphasor® Module is a half-height, 2-channel module 

that provides Keyphasor signals to the Monitor modules in a 3500 Rack.  The 

Keyphasor module receives analog input signals from proximity probes or 

magnetic pickups and converts them to conditioned digital signals that indicate 

when the Keyphasor mark on the shaft is in line with the probe.  The 3500 

Monitoring System can accept 4 such Keyphasor signals, which the 3500 

Monitoring System modules and external diagnostic equipment use to measure 

such vector parameters as 1X amplitude and phase. 

A 3500 Rack may have 1 or 2 Keyphasor Main Modules in a normal configuration, 

3 or 4 Keyphasor Main Modules for a paired Keyphasor configuration, and 1 of 5 

types of Keyphasor I/O Modules installed.

Keyphasor Main Module (front panel buffered output connectors indicated) Keyphasor I/O Module, with Isolated Internal Terminations Keyphasor I/O Module, with Isolated External Terminations Keyphasor I/O Module, with Non-Isolated Internal Terminations Keyphasor I/O Module, with Non-Isolated External Terminations Keyphasor I/O Module, with Barriers (Non-Isolated, Internal Terminations)

3500/25 Enhanced Keyphasor Module Operation and Maintenance Manual 

Regardless of the Event Ratio you specify, both the input Keyphasor signal and generated Processed Rack Signals have limitations that, among other things, affect the Channel and Module OK Statuses.  The Specification section of this manual details these limitations. You may specify the Event Ratio as a positive, real number (i.e., an integer and/or fractional number) that is either less than or greater than, but not exactly equal to, 1.0.  Although the software will not allow you to specify an Event Ratio of exactly 1.0, you can functionally achieve this by specifying the Events Per Rev with a value of 1 with the Event Setup option.  This configuration supports the majority of typical customer applications and achieves maximum system performance.  This also eliminates what would otherwise be a redundant means of specifying unity Keyphasor rate processing. Noted that, in general, the system is better able to track the input for higher Event Ratio numeric values, since it has more "information" in the form or input pulses with which to work.  This allows the system to better to respond to speed fluctuations or ramping conditions as it tracks the input. There are a few extra considerations to remember when you specify an Event Ratio less than 2.0.  The design of the digital signal processing algorithm uses 2 fundamentally different strategies, one for Event Ratios equal to or greater than 2.0 (which essentially implies frequency division), and the other for Event Ratios less than 2.0 (which implies frequency multiplication).  The DSP code automatically selects the algorithm based on the programmed Event Ratio for each channel.  The large majority of applications will require the Keyphasor module to use an Event Ration much greater than 2.0 to divide down the input signal.  Because of this the DSP code has been optimized to support these applications.  This improves the module’s transient response for frequency division, but degrades the response for frequency multiplication.  For this reason, you should not expect the Enhanced Keyphasor Module to exhibit any reasonable transient response for Event Ratios approaching or less than 2.0. Frequency multiplication processing has 2 additional side effects that are not present when you specify an Event Ratio of 2.0 or greater.  These 2 side-effects are similar in effect and result from the limitations that are inherent in attempting to generate multiple output pulses in response to a single input pulse (or sequence of pulses), which is the essence of frequency multiplication.   1. 2. The Enhanced Keyphasor Module may require a significant amount of synchronization time from when a signal is first applied to the input to a Keyphasor channel to when the first Processed Signal output appears.   Generally speaking, the more significant digits you specify to the right of the decimal point in the Event Ratio, the longer the DSP may take to synchronize to the input and generate output pulses in response.   When the Enhanced Keyphasor Module loses the input Keyphasor signal, a multiplied output at the programmed rate may persist for some time after the input stimulus is lost.

Software Configuration Options This section 

discussed the Keyphasor Module configuration options in detail.  In addition to describing the options, this section provides figures that depict screen views of the 3500 Rack Configuration software.  Several examples illustrate the various option choices on the Keyphasor Module configuration screen.   Depending on the numeric values entered for some configuration parameters, the Rack Configuration Software may restrict certain options, make options unavailable, and/or automatically "force-select" some options.