Energy Reduction Maintenance Settings (ERMS) - MicroLogic Active User Guide

Presentation

The ERMS function is used to reduce instantaneous overcurrent protection settings so that the circuit breaker trips as soon as possible when a short circuit occurs. Minimizing the time between short circuit and trip helps to reduce the risk of injury when qualified electrical personnel are near energized equipment.

When the ERMS function is engaged, the ERMS protection settings replace the standard instantaneous overcurrent protection settings.

Availability

The ERMS function is available on MicroLogic Active 2.0, 5.0 and 6.0 control units for IEC standard.

Operating Principle

The ERMS function can be engaged or disengaged by using the ERMS button.

While the ERMS function is engaged:

The ERMS LED (A) is lit in blue.
The LSIG home screen is blue.
The Quick View screens are blue.
All other screens are not blue.

Use-case Examples

The conditions of operation of electrical installations are specified by national regulations (for example, NPFA70E for USA, EN 50110 for Europe). These regulations require an assessment of electrical risk before carrying out any operation. The assessment must specify when the ERMS function should be implemented and engaged.

Whenever possible the electrical installation should be de-energized. When working in the vicinity of live parts without all doors or panels of the switchboard closed and secured, the ERMS function can be engaged to reduce the consequences of a short circuit. A risk assessment specific to each situation must be carried out, even when the ERMS function is used.

The following table gives examples of use-cases inside or close to a switchboard, where engaging the ERMS function is recommended. The recommendations are based on the assumptions that:

The ERMS function is embedded in the upstream device on the supply side of the switchboard in question
The switchboard has only one supply.

Operation	Location
Addition of device in spare slot in the switchboard	Inside switchboard
Thermal inspection	Inside switchboard
Measurement reading inside switchboard, requiring opening of door or panels	Inside switchboard
Measurement with portable equipment (for example, voltage presence, phase rotation, power quality)	Inside switchboard
First energization or re-energization of the equipment	In electrical room, less than 0.3 m (12 in) from switchboard
Device unlocking with padlock or key	In electrical room, less than 0.3 m (12 in) from switchboard
Device closing	In electrical room, less than 0.3 m (12 in) from switchboard

Engaging the ERMS Function

The ERMS function can be engaged by using the ERMS button. See Engaging the ERMS Function.

Disengaging the ERMS Function

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH Prior to disengaging ERMS: Carefully inspect your work area, and remove any tools and objects left inside the equipment. Ensure that all personnel are away from the equipment, and devices, doors, and covers are in place. Failure to follow these instructions will result in death or serious injury.

The ERMS function can be disengaged by using the ERMS button. See Disengaging the ERMS Function.

ERMS Settings

When the ERMS function is engaged, the standard setting for instantaneous overcurrent protection is overridden by the default ERMS setting for instantaneous overcurrent protection:

Protection function	Setting	Unit	Default ERMS value	MicroLogic Active type
Instantaneous overcurrent protection	Ii	A	2.0 x In	MicroLogic Active 5.0 and 6.0
Instantaneous overcurrent protection	Ii	A	1.5 x Ir	MicroLogic Active 2.0

The default ERMS setting for instantaneous overcurrent protection cannot be modified.

The other protection functions use standard protection settings.

Predefined Events

The function generates the following predefined events:

Code	Event	History	Severity
0x0C03 (3075)	ERMS engaged	Protection	Low

Predefined events cannot be modified by the user. For general information about events, refer to Event management.