Reverse Active Power Protection (ANSI 32P)

Presentation

Reverse active power protection (ANSI 32P) detects, and trips the circuit breaker, when a synchronous power generator connected to an external network, or running in parallel with other generators, operates as a synchronous motor. It can also be used to monitor the amount of active power exchanged between two parts of an electrical network, with associated alarms, load shedding or tripping as soon as the flow of active power in the selected direction exceeds the set value.

Prerequisites

Reverse active power protection is available when the ANSI 32P - Reverse Active Power Protection Digital Module is purchased and installed on a MicroLogic X control unit.

Reverse active power protection requires an external 24 Vdc power supply.

Reverse active power protection is compatible with:

oMicroLogic 2.0 X, 5.0 X, 6.0 X, and 7.0 X control units for IEC standard

oMicroLogic 3.0 X, 5.0 X, and 6.0 X control units for UL standard

oMicroLogic X control units with firmware version greater than or equal to 002.000.002. Earlier firmware versions need to be updated.

Data from the Digital Module is available remotely through IFE/EIFE or IFM communication interfaces, if the IFE/EIFE or IFM firmware version is compatible with the Digital Module. For more information, refer to firmware compatibility of the communication interfaces.

Operating Principle

Reverse active power protection calculates the active power with the RMS values of the voltages and currents. A time delay is associated with the protection. The positive sign of active power is defined by the power sign setting. The same sign is used for active power measurement.

By default, the MicroLogic X control unit assigns the sign + to the active power when the transit of the active power flows from upstream (top) to downstream (bottom) of the circuit breaker. The sign - is assigned when the transit circulates from downstream (bottom) to upstream (top) of the circuit breaker. This assumes that the power source feeding the installation is connected on the top side of the circuit breaker (top-fed circuit breaker).

NOTE: When the power source is connected on the bottom side of the circuit breaker (bottom-fed circuit breaker), the power sign setting assigned by default must be changed.

The protection trips when all of the following conditions are met:

oThe active power is negative

oThe value of the active power exceeds the setting

oThe time delay is elapsed

Tripping Curve Characteristic

To avoid nuisance tripping, the protection does not trip in the case of very low power factor, corresponding to |Q/P| > 32 (87.2° < φ < 92.8° or 267.2° < φ < 272.8°)

The figure below shows three examples with Rp = 100 kW, Rp = 500 kW, and Rp = 1000 kW.

 

T   Trip

NT   No trip

Inhibiting Protection

To inhibit the reverse active power protection both the following conditions must be met:

oInhibition is enabled on the reverse active power protection by setting the Inhibition parameter to ON.

oInhibition of optional protections is activated by an input of the IO module. The function Inhibit Optional Protection must be assigned to an input of the IO module.

For more information about inhibiting optional protections, refer to Enerlin'X IO - Input/Output Application Module for One Circuit Breaker - User Guide.

Setting the Protection

The reverse active power protection settings are:

oRp mode: enables (ON) or disables (OFF) the protection

oRp action: sets the result of reverse active power protection as trip or alarm

oRp inhib: enables (ON) the protection to be inhibited by IO module

oRp: total active power threshold

otRp: time delay

They can be set as follows:

oWith EcoStruxure Power Commission software (password-protected)

oWith EcoStruxure Power Device app (password-protected)

The dual settings function does not apply to reverse active power protection. When the dual settings function is enabled, reverse active power protection settings are the same whether set A or set B settings are activated.

Protection Settings

The following reverse active power protection settings are recommended for the protection of networks powered by turbines or diesel engines:

Protection Characteristics

Characteristics of reverse active power protection:

oDefinite time delay

oInstantaneous reset time

oHysteresis: fixed 98%

oMinimum breaking time 50 ms

oMaximum breaking time 140 ms with time delay set to 0 s

Predefined Events

The function generates the following predefined events:

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

Protection events are generated as follows:

oThe start event is generated when the protection picks up.

oThe operate event is generated when the protection time delay elapses.

The operate event is not generated when the optional protection is inhibited.

oThe trip event is generated when the circuit breaker tripping voltage release (MITOP) activates.

The trip event is not generated when:

oThe optional protection is set in alarm mode

oThe optional protection is inhibited

Recommended Actions

Resetting a Trip Event

For information about resetting the circuit breaker after a trip due to an electrical fault, refer to the relevant document:

oMasterPact MTZ1 - Circuit Breakers and Switch-Disconnectors - User Guide

oMasterPact MTZ2/MTZ3 - Circuit Breakers and Switch-Disconnectors - User Guide