Page 19 - GuardII+ Series 4208 Platform Flux User Manual

GuardII+ Flux Card Operation

• Measurement results per coil (for round rotor machines)

• Alert status
Refer to Section 8.2 for details of the Modbus flux register addresses.

4.7. GuardII+ Alerts

Alerts in a GuardII+ flux system are based on the alert thresholds configured in IAM; when
any measurement produces data that shows a flux density difference greater than the
configured thresholds, the Alert is asserted.

NOTE:
There are two configurations that need to be completed using IAM for the
Alert feature to function fully:
• First, there is a general Alert Relay behavior that must be set to a
selection other than ‘Disabled’; if the Alert Relay behavior is not
configured, then the Alert Relay will not function, although Archived
measurements and Modbus data will still report an Alert when it

occurs.
• Second, the alert thresholds must be set.
Refer to Section 6.3 for details on GuardII+ configuration.

A measurements’ flux Alerts can identify a specific pole and/or coil showing signs of a
problem, but only when the system is used to its full potential; a shaft trigger signal is needed
to properly identify poles when a machine has more than 2 poles.

4.7.1. Salient Pole Alerts
Alerts on salient pole machines are based on the normalized pole-to-pole flux density.
Typically, a pole shows some sign of a problem with a flux density change of 3% although this
can vary slightly from machine to machine.

4.7.2. Round Rotor Alerts

Alerts on round rotor machines are based on comparing the amplitude of the peak flux
values for each coil to the peak flux amplitude for that same coil on the opposite pole.
Typically, a coil shows some sign of a problem with a flux density change of 3% although this
can vary slightly from machine to machine.

4.7.3. Alert Relay

GuardII+ is equipped with a solid-state Alert Relay that can be programmed with one of
five behavior options using IAM:

• Disabled – the Alert Relay is not used.
• Normally Open, Latching – if there is no Alert condition, the relay contacts are open.
When an Alert is detected the relay will close and stay closed until reset.

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