Series-659

Supported Applications

The Dwyer Series 659 Push-Button Temperature Transmitters are head-mounted devices designed to connect directly to standard temperature sensors, including thermocouples (Types J, K, T), RTDs (Pt100/Pt1000), and thermistors. These transmitters linearize the sensor signal and convert it into a 4 to 20 mA output for process monitoring and control systems.

Engineers select this series for applications requiring in-head mounting within standard temperature probe enclosures or termination heads. The units are configured via an on-board push-button interface, allowing field ranging and calibration without external tools.

Operating Conditions & Performance

The Series 659 operates across a wide range of input temperatures depending on the sensor type selected:

• Thermocouple (Type J, K, T): Ranges from -328 to 2498°F (-200 to 1370°C).
• RTD Input: Supports ranges up to -328 to 1562°F (-200 to 850°C) for Pt100/Pt1000 sensors.
• Thermistor Input: Covers -13 to 257°F.

Ambient operating conditions are specified as -4 to 158°F (-20 to 70°C) with a maximum humidity of 80% RH. The transmitter features an adaptive filter factor and provides a sample rate of 500 ms, reaching 90% of the final value in approximately 1 second.

Accuracy specifications vary by input type:

• T/C Models: ±0.04% FS, ±0.04% of reading, or ±0.5°C (whichever is greater).
• RTD Models: ±0.2°C ±0.1% of range.
• Thermistor Models: ±0.25°F (±0.1°C).

The device is protected against reverse connection and over-voltage, with upscale burnout output at 22 mA if the sensor input is disconnected.

Configuration Options

Series 659 transmitters are available in three primary configurations to match specific sensor technologies:

• Model 659TC-1: Accepts Thermocouple inputs (Types J, K, T) and mV signals.
• Model 659RTD-1: Designed for Pt100 resistance sensors with 2 or 3-wire connections.
• Model 659TH-1: Configured for Thermistor inputs (2252Ω).

All models provide a two-wire, loop-powered 4 to 20 mA sink output. Electrical connection is made via screw terminals located on the top face of the unit. The transmitter dimensions are Ø43.0 mm diameter by 21.0 mm depth (or approximately 1-5/8 in base diameter), designed to fit inside a DIN standard probe head enclosure.

Power supply requirements range from 10 to 30 VDC, with typical loop resistance limits of 700 Ω @ 24 VDC for T/C models and 800 Ω @ 24 VDC for RTD models. An optional NEMA 4X Aluminum Transmitter Enclosure (Accessory A-709) is available to provide additional environmental protection.

Key Product Differences

The primary distinction between Series 659 variants lies in the input sensor technology and associated accuracy profiles. The 659TC-1 supports multiple thermocouple types (J, K, T) with selectable fixed ranges via push-button menus, while the 659RTD-1 is optimized for Pt100 sensors with linearization per BS EN 60751 standards.

While all models share the same physical footprint and output signal type (4 to 20 mA), they differ in internal calibration curves and maximum loop resistance capabilities. The series conforms to EC directive BS EN 61326 : 1998 when installed in a termination head providing at least IP20 protection.