Section 1– Introduction

MicroLogic™ 5 and 6 electronic trip units offers monitoring of alarms, quality indicators and maintenance indicators. This makes it possible to:

• Identify overloaded equipment

• Perform predictive maintenance

  • Time-stamped historical logs allow analysis of system operation

  • Pre-alarms allow early detection of potential events

  • Local or remote alarm of events allow quick analysis and action

• Preventative maintenance

  • Log of maintenance operations, including contact wear, operating hours, and load profiles

MicroLogic A and E trip units have indicators for, among others, the number of operating cycles, contact wear and operating times (operating hours counter) of the PowerPacT™ H-, J-, and L-frame circuit breakers.

It is possible to assign an alarm to the operating cycle counter to plan maintenance. The various indicators can be used together with the trip histories to analyze the level of stresses the device has been subjected to. The information provided by the indicators cannot be displayed on the MicroLogic trip unit LCD. It is displayed on the PC through the communication network.

When the MicroLogic trip unit, with or without a front display module, is connected to a communication network, all information can be accessed using a PC with the appropriate software installed.

Two types of time-stamped event tables

• Protection settings

• Minimums / maximums

Display of alarms and tables

The time-stamped history and event tables may be displayed on a PC through the communication network.

Embedded memory

MicroLogic A and E trip units have a non-volatile memory that saves all data on alarms, histories, event tables, counters and maintenance indicators even if power is lost.

Each circuit breaker equipped with a MicroLogic 5 or 6 trip unit can be identified using the communication network:

• serial number

• firmware version

• hardware version

• device name assigned by the user.

This information together with that previously described provides a clear view of the state of the installed devices.

• Contact wear
  Each time PowerPacT H-, J-, and L-frame circuit breakers open, the MicroLogic 5 / 6 trip unit measures the interrupted current and increments the contact-wear indicator as a function of the interrupted current, according to test results stored in memory. Breaking under normal load conditions results in a very slight increment. The indicator value may be read on the front display module. It provides an estimation of contact wear calculated on the basis of the cumulative forces affecting the circuit breaker. When the indicator reaches 80%, it is advised to replace the circuit breaker to ensure the availability of the protected equipment.

• Circuit breaker load profile
  MicroLogic 5 / 6 trip units calculate the load profile of the circuit breaker protecting a load circuit. The profile indicates the percentage of the total operating time at four current levels (% of In):

  • 0 to 49% In

  • 50 to 79% In

  • 80 to 89% In

  • ≥ 90% In

  • This information can be used to optimize use of the protected devices or to plan ahead for expansion.