GE Multilin 239-RTD-AN Motor Protection Relay with Up to 12 RTD Inputs

Product Overview

The GE 239-RTD-AN is a sophisticated motor protection relay from the GE Multilin 239 series, engineered to provide comprehensive protection for three-phase AC motors in demanding industrial environments . This relay combines electrical fault protection with precision thermal monitoring through Resistance Temperature Detector (RTD) sensor technology, making it an essential component for safeguarding valuable motor assets from both electrical and thermal damage . The 239-RTD-AN continuously monitors motor current, voltage, and temperature, detecting abnormalities such as overload, under/overvoltage, single-phasing, ground faults, rotor stall, and mechanical jam conditions .

The model designation reveals the core capabilities of the GE 239-RTD-AN: the RTD suffix indicates the presence of the RTD option for direct temperature monitoring via platinum, nickel, or copper sensors installed in motor windings and bearings . The AN suffix denotes the analog output option, providing a programmable isolated 4-20mA signal that can transmit thermal capacity, percent load, or phase current data to PLC or DCS systems . With RS485 Modbus RTU communication capabilities, the 239-RTD-AN integrates seamlessly into SCADA and industrial control networks, enabling remote parameter adjustment, fault diagnosis, and real-time data acquisition .

The GE 239-RTD-AN is designed for installation within motor starters, serving as a pilot device that triggers contactors or circuit breakers under fault conditions without carrying the main motor current . Its compact form factor and wide power supply range (90-300 VDC or 70-265 VAC) ensure compatibility with diverse starter configurations . As a legacy product from GE Multilin’s renowned protection relay portfolio, the 239-RTD-AN continues to be widely deployed across power generation, oil and gas, water treatment, and heavy manufacturing facilities

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Description

Technical Specifications

Parameter Name	Value
Product Model	239-RTD-AN
Manufacturer	General Electric (GE Multilin)
Product Type	Motor Protection Relay / Motor Management Relay
Phase Current Input	1A and 5A secondary CT inputs
Current Measurement Range	0.1 to 11 × CT primary value
Frequency Range	20–300 Hz
Ground Current Input	5A CT or 50:0.025 CT
Control Power Supply	90-300 VDC / 70-265 VAC (MOD501: 20-60 VDC)
Power Consumption	20 VA typical
RTD Inputs	Up to 3 RTDs (Pt, Ni, Cu types)
RTD Temperature Range	-50°C to +250°C
Analog Output (AN)	Single isolated: 0-1mA, 0-20mA, or 4-20mA
Communication Interface	RS485, Modbus RTU protocol
Alarm/Relay Outputs	Configurable relay outputs
Overload Trip Accuracy	±1% of displayed value
Operating Temperature	-40°C to +70°C
Protection Rating	IP67
Display	40-character LCD with LED status indicators
Certifications	UL, CE, CSA

Main Features and Advantages

Comprehensive motor protection suite: The GE 239-RTD-AN delivers complete protection for three-phase motors through 15 selectable overload curves, short-circuit protection, rotor stall detection, mechanical jam protection, single-phasing/unbalance protection, ground fault detection, undercurrent monitoring for pump dry-run protection, and thermal overload warning . This extensive protection suite ensures that the 239-RTD-AN can be precisely configured to match specific motor characteristics and application requirements.

Advanced RTD temperature monitoring: The RTD capability of the 239-RTD-AN enables direct thermal measurement of critical motor components . Up to three RTD sensors can be connected to monitor stator winding temperatures, bearing temperatures, or ambient conditions, providing early warning of overheating conditions before insulation damage occurs . This real-time temperature data is displayed on the front panel LCD and can be transmitted via the analog output, enabling predictive maintenance strategies.

Programmable analog output (AN): The analog output option provides a versatile interface for process control integration. The GE 239-RTD-AN outputs a programmable isolated 4-20mA, 0-20mA, or 0-1mA signal proportional to selected parameters including thermal capacity, percent full load, phase current, or RTD temperature readings . This feature enables direct interfacing with PLC analog input modules, strip chart recorders, or process controllers without additional signal conditioning.

Modbus RTU communication: The RS485 communication port of the 239-RTD-AN supports the industry-standard Modbus RTU protocol, enabling integration with SCADA systems, building management platforms, and industrial IoT networks . Remote monitoring of all values, setpoint programming, fault command issuance, and diagnostic data retrieval are all supported, significantly reducing the need for local operator intervention .

Diagnostic and data logging capabilities: The GE 239-RTD-AN stores fault event history, motor operating hours, and maximum motor current during last start . Trip diagnostic information helps operators quickly identify fault root causes and resume operations . The thermal memory lockout feature prevents operator misuse of motors and equipment by enforcing cooldown periods .