Advanced Voltage Protection in RC Series Recloser Controllers

Voltage disturbances such as sags, swells, and sustained over/under voltage conditions are common in modern distribution networks. These events can arise from load fluctuations, switching operations, distributed energy resource (DER) integration, or system faults, and can lead to equipment damage, reduced performance, and network instability.

NOJA Power’s RC-10, RC-15, and RC-20 Recloser Controls incorporate a comprehensive suite of configurable voltage protection elements designed to detect abnormal system conditions and automatically respond to prevent equipment damage and extended outages.

The voltage protection capability is implemented through a suite of ANSI-standard protection elements, each designed to address specific network conditions.

Under Voltage Protection (ANSI 27)

• UV1 – Phase Under Voltage

Operates on positive sequence voltage and is commonly used for load shedding applications.

• UV2 – Line-to-Line Under Voltage

Detects voltage drops between phases, suitable for protecting sensitive downstream loads.

• UV3 – Loss of Supply

Detects loss of system voltage and/or current, enabling feeder isolation and preventing backfeed in automation schemes.

• UV4 – Voltage Sag Protection

Detects voltage sags within a configurable window (min/max thresholds) over a defined time period, allowing controlled response to transient disturbances.

Over Voltage Protection (ANSI 59)

• OV1 – Phase Over Voltage

Monitors positive sequence voltage exceeding a defined threshold.

• OV2 – Line-to-Line Over Voltage

Detects phase-to-phase overvoltage conditions.

• OV3 – Neutral Displacement (59N)

Used in networks with high impedance grounding to detect earth faults via neutral shift.

• OV4 – Negative Sequence Over Voltage

Detects voltage imbalance, useful for identifying conditions such as broken conductors.

These elements allow utilities to detect both transient and sustained voltage abnormalities and apply selective protection strategies depending on network conditions.

All voltage protection settings can be configured and monitored via NOJA Power’s Control Management System (CMS) and Device Configuration Manager (DCM), enabling flexible deployment and integration with SCADA systems.

“Voltage protection is a critical component of modern distribution automation,” said Neil O’Sullivan NOJA Power Managing Director.

“With a full suite of ANSI-compliant voltage elements, flexible configuration, and advanced operating logic, NOJA Power’s RC Series Recloser Controls provide utilities with the tools required to maintain stable voltage profiles and improve overall network reliability.”