2CDE165011R2001 ABB E236-US2.1 Undervoltage Monitoring Relay 1CO

Why Choose the ABB E236-US2.1 Undervoltage Monitoring Relay?

The ABB E236-US2.1 is a compact undervoltage monitoring relay with one changeover contact (1CO), designed to supervise phase-to-neutral voltages in electrical switchgear and distribution systems. Part of the ABB E236 / System pro M compact range, it provides a straightforward method of detecting undervoltage conditions and transferring a relay contact for signalling or control purposes.

The E236-US2.1 monitors three phase-to-neutral voltages and provides an adjustable undervoltage threshold from 160 to 240 V AC. A fixed 5% hysteresis supports stable switching around the selected threshold, while the device has a 200 ms switch-off delay to provide a defined response when a monitored voltage falls below the set level.

Unlike the two-changeover-contact E236-US2, the E236-US2.1 provides a single 1CO output contact while occupying only 17.5 mm of DIN rail space. Its compact one-module construction makes it well suited to switchboards, distribution boards and control panels where reliable undervoltage supervision is required without using unnecessary panel space.

Key Advantages

• Continuous three-phase undervoltage monitoring from phase to neutral.
• Adjustable threshold from 160 to 240 V AC for application-specific voltage supervision.
• 1CO changeover output for signalling, interlocking or control functions.
• Fixed 5% hysteresis helps prevent unstable relay operation around the threshold.
• 200 ms switch-off delay provides a defined response to undervoltage conditions.
• Suitable for both single-phase and three-phase monitoring arrangements when connected according to ABB requirements.
• Compact 17.5 mm single-module design conserves DIN rail space.
• Designed for integration with ABB System pro M compact electrical assemblies.

Key Features

• ABB E236 undervoltage monitoring relay series.
• 1 changeover contact (1CO).
• 160–240 V AC adjustable undervoltage threshold.
• 5% fixed hysteresis.
• 200 ms switch-off delay.
• Supports three-phase-to-neutral voltage monitoring.
• Can be used for single-phase monitoring when all measuring inputs are connected appropriately.
• Neutral conductor required for correct operation.
• DIN rail mounting in accordance with modular switchgear practice.
• 17.5 mm width occupies only one modular space.
• Compact 87 × 17.5 × 60 mm housing.
• System pro M compact format for professional distribution and control installations.

Reliable Undervoltage Supervision in a Single Module

The ABB E236-US2.1 supervises the connected phase voltages relative to neutral and responds when a monitored voltage falls below the selected threshold. Its adjustable 160–240 V AC range allows the switching level to be matched to the requirements of the installation, while the fixed hysteresis helps provide stable relay operation as the supply voltage changes around that threshold.

For three-phase monitoring, each measuring input is connected to its corresponding phase and a neutral conductor must always be connected. Where single-phase measurement is required, ABB specifies that the measuring inputs must be connected to the phase so that the required voltage is present at every measuring input. The single changeover output can then be incorporated into alarm, interlocking or control circuitry according to the system design.

Typical Applications

• Three-phase switchgear undervoltage monitoring.
• Electrical distribution boards and switchboards.
• Industrial control and automation panels.
• Building electrical distribution systems.
• Power-supply status signalling.
• Undervoltage alarm and interlocking circuits.
• Equipment requiring phase-to-neutral supply supervision.