0614IB1802

Arc Energy Reduction with MTZ Energy Reduction Maintenance Settings (ERMS)

N = Normal: Tripping curve for standard protection functions with ERMS disengaged.

R = Reduced: Tripping curve for standard protection functions with ERMS engaged.

MasterPact™ MTZ circuit breakers provide an Energy Reduction Maintenance Settings (ERMS) function to reduce the arc flash incident energy and meet 240.87 2017 NEC requirements. The ERMS allows the user to set the MTZ circuit breaker control unit to "no intentional delay" to reduce the clearing time while work is done within an arc flash boundary as defined in the NFPA 70E-2015, Standard for Electrical Safety in the Workplace, and then set the control unit back to a normal setting after the potentially hazardous intervention is completed.

MasterPact MTZ circuit breakers provide two means of engaging the ERMS function when used with the purchased ERMS digital module (LV850009)

  • Use of a physical switch

  • Use of the EcoStruxure Power Device App for Android and iOS devices

The physical switch option allows the user to remotely engage/disengage the circuit breaker’s ERMS function.

The EcoStruxure Power Device App allows a user to engage and disengage the ERMS function via Bluetooth wireless communications using an Android or iOS compatible device.

For Android devices, the ERMS can also be engaged/disengaged using the Micrologic X control unit’s USB On The GO (OTG) link.

When engaged through the EcoStruxure Power Device App, a digital lock is created between the EcoStruxure Power Device App and the Micrologic X control unit.

  • The “digital lock” sends a unique and randomly generated key from the control unit to the smart device being used to engage the ERMS function. This key prevents another user from disengaging the ERMS from a different smart device.
    NOTE: For Micrologic X control units with firmware versions < 3.0 and EcoStruxure Power Device App versions (Android > 3.0, iOS > 3.0), the Micrologic X firmware must be upgraded to version 3.0 or higher to be able to use the ERMS function.

  • The smart device that engages the ERMS function must be the same device that disengages the ERMS function.
    If the smart device breaks, is lost, or is no longer present, the ERMS function can be forced to disengaged. (Contact Schneider field services for more information on Micrologic X control units with firmware versions less than 3.0.)

  • The EcoStruxure Power Device App can also add a digital lock to systems that use the physical switch. In these systems, both the ERMS physical switch and the EcoStruxure Power Device App must be set to disengaged before the control will become disengaged (see ERMS Operation table below).

ERMS Operation

ERMS Switch

EcoStruxure Power Device App

Control Unit ERMS State

Indicator Lamp in ERMS Switch and/or Remote Indicator

Control Unit HMI Backlight

ERMS LED on Control Unit’s HMI

Disengaged (Switch Closed)

Disengaged

Disengaged

OFF

NORMAL

OFF

Engaged (Switch Open)

Disengaged

Engaged

ON

ON—Blue

ON—Blue

Disengaged (Switch Closed)

Engaged

Engaged

ON

ON—Blue

ON—Blue

Engaged (Switch Open)

Engaged

Engaged

ON

ON—Blue

ON—Blue

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