Allen‑Bradley 193‑EC2AB E3 Plus Electronic Overload Relay

The Allen‑Bradley 193‑EC2AB is an E3 Plus electronic overload relay designed for motor protection in industrial automation systems. This device combines precise overload protection, phase loss detection, and ground fault monitoring with built‑in communication capabilities. The current range is adjustable from 1 A to 5 A, making it suitable for small to medium three‑phase induction motors. The relay operates on 24 V DC and is compatible with DeviceNet networks, allowing remote monitoring and configuration. The E3 Plus series is known for its accuracy, reliability, and advanced diagnostic features, reducing downtime and improving machine safety.

Technical Specifications

The 193‑EC2AB has an adjustable current range of 1 A to 5 A (full load current setting). The trip class is selectable: Class 10, 20, or 30. Thermal memory retention time is 5 minutes (typical). The relay includes phase loss protection (trips within 3 seconds), phase imbalance protection (adjustable threshold), and ground fault protection (requires optional ground fault module). Communication protocol: DeviceNet (Group 2 only, slave). Power supply: 24 V DC (19.2‑28.8 V), consumption 1.9 W typical. Output contacts: one normally open (NO) and one normally closed (NC) auxiliary relay. The relay also provides a 4‑20 mA analog output (optional, requires expansion module). Dimensions: 83 mm (H) × 45 mm (W) × 101 mm (D). Protection rating: IP20 (open type). Operating temperature: 0 °C to 60 °C. Storage: -40 °C to 85 °C. Humidity: 5‑95% non‑condensing.

Key Features

• Adjustable current range: 1 A to 5 A for small motor applications

• Selectable trip classes: Class 10, 20, or 30

• Electronic thermal overload protection with thermal memory

• Phase loss and phase imbalance detection

• Built‑in DeviceNet communication for remote monitoring and configuration

• 24 V DC control voltage

• One normally open and one normally closed auxiliary output

• LED status indicators for trip, warning, and communication

• Reset options: manual or automatic (selectable)

• Compatible with Bulletin 193‑EC3 grounding module for ground fault protection

Protection Functions

The E3 Plus relay continuously measures the three phase currents using internal current transformers. The electronic thermal model accurately simulates motor heating and cooling, preventing nuisance tripping during momentary overloads. The thermal memory retains the thermal state even if the relay loses power, ensuring proper protection after a restart. Phase loss detection identifies a missing phase and trips within 3 seconds. Phase imbalance protection triggers when the current difference between phases exceeds a programmable threshold (default 15%). A ground fault protection module (193‑EC3, sold separately) can be added to detect leakage currents as low as 0.5 A. The relay also includes a jam detection function that trips if the motor current exceeds a settable percentage of the full load current for a defined time.

DeviceNet Communication

The integrated DeviceNet interface allows the 193‑EC2AB to be connected to a DeviceNet network as a slave device. The relay supports I/O polling and explicit messaging. The following data is available to the master: motor current (average and individual phases), thermal capacity used, trip status, warning status, phase loss status, and ground fault status. The master can also read and write parameters such as full load current, trip class, and reset mode. The DeviceNet address is set using two rotary switches on the front of the relay (0‑63). The baud rate can be 125, 250, or 500 kbit/s, automatically detected or set via software. The relay includes a green NET LED for network status and a green MOD LED for module status.

Applications

The 193‑EC2AB is suitable for protecting small three‑phase motors in applications such as small conveyors, pumps, fans, compressors, packaging machinery, and material handling equipment. The adjustable current range (1‑5 A) makes it ideal for fractional horsepower motors up to about 2 HP at 480 V. The DeviceNet communication enables integration into plant‑wide control systems, allowing maintenance personnel to remotely monitor motor current and thermal capacity, and to reset overloads without physical access to the relay. The electronic overload offers greater accuracy and repeatability than traditional bimetallic relays, reducing downtime caused by false trips.

Installation and Configuration

The 193‑EC2AB mounts directly onto a Bulletin 100‑C or 100‑E contactor (sizes C, D, E, F) or can be used stand‑alone with DIN rail mounting. For direct mounting, the relay plugs into the contactor's rear accessory slot. For stand‑alone use, a separate mounting adapter (193‑ECM1) is required. Connect the three phase wires to the relay's line (L1, L2, L3) and load (T1, T2, T3) terminals. Connect 24 V DC to the A1 and A2 terminals. The auxiliary output contacts (95‑96 normally closed, 97‑98 normally open) are wired in series with the contactor coil or PLC input. Set the DeviceNet node address using the rotary switches. Configure the full load current (Ie) using the potentiometer on the front (scale 1‑5 A). Select trip class using a DIP switch inside the relay. The relay also has a test/reset button for functional testing and manual reset.

Diagnostics and Maintenance

The front panel LEDs provide immediate diagnostic information: a green POWER/TRIP LED flashes green during normal operation and turns red when tripped; a yellow WARNING LED indicates the motor is approaching trip level (>95% thermal capacity); a green NET LED indicates DeviceNet communication status; a green MOD LED indicates module status. The relay can be manually reset by pressing the reset button after the trip condition has cleared. For automatic reset, set the DIP switch accordingly. The relay requires no routine maintenance beyond periodic cleaning of ventilation slots and verification of terminal tightness. The internal thermal memory algorithm is self‑calibrating and does not require field calibration.

Environmental and Compliance

The 193‑EC2AB is UL, CSA, and CE certified. It meets IEC 60947‑4‑1 and NEMA ICS 2 standards. It is RoHS compliant. Operating temperature: 0 °C to 60 °C. Storage: -40 °C to 85 °C. Humidity: 5‑95% non‑condensing. Vibration: 2g (10‑55 Hz). Short‑circuit withstand rating: 5 kA with appropriate upstream fuses or circuit breakers. The relay is rated IP20 and must be installed in a control cabinet.

Conclusion

The Allen‑Bradley 193‑EC2AB E3 Plus electronic overload relay provides reliable, adjustable motor protection for small industrial motors. Its 1‑5 A current range, selectable trip classes, and DeviceNet communication make it a flexible and smart choice for modern automation systems requiring remote monitoring and diagnostics. The electronic design eliminates the drift and inaccuracies of thermal overloads, ensuring consistent protection and reducing unplanned downtime.