Watlow 997D-11CC-JURG SERIES 997 Vertical Limit Control

Watlow 997D-11CC-JURG | SERIES 997 Vertical Limit Control

The Watlow 997D-11CC-JURG is a high-reliability, 1/8 DIN vertical limit controller. Unlike standard temperature controllers that regulate heat, the SERIES 997 is a dedicated safety device.

Its primary function is to act as a “watchdog,” monitoring for over-temperature or under-temperature conditions and physically breaking the circuit to prevent equipment damage or fire.

The “D” in the model number signifies its digital display, providing clear, real-time feedback for safety-critical environments.

Technical Parameter Table

Unique Product Description

The 997D-11CC-JURG is defined by its FM (Factory Mutual) approval. This is not just a standard certification;

it means the device is rigorously tested to meet the high-safety requirements for industrial insurance standards.

The “JURG” suffix denotes a specific configuration of range and units (typically Fahrenheit) and a latching mechanism that requires a manual reset once a limit is tripped.

This ensures that an operator must investigate the cause of the over-temperature before the process can resume, adding a critical layer of human oversight to automated systems.

Product Advantages and Features

Redundant Safety: Functions as an independent hardware cut-off, separate from the primary PID controller.

Dual Output Relays: Allows for one relay to cut power to the load while the second relay triggers a remote alarm or PLC input.

Manual/Auto Reset: Features a front-panel reset button, but can also be wired for a remote external reset.

High Contrast Display: The bright red LED ensures the “Limit” status is visible even from across a dark factory floor.

Simplified Setup: Uses straightforward hardware jumpers and a clear menu for setting the limit setpoint, reducing “configuration fatigue.”

Application Cases

Industrial Ovens & Furnaces: Acts as the primary safety shut-off to prevent runaway heating if the main contactor welds shut.

Boiler Systems: Monitoring for high-pressure or high-temperature steam conditions to prevent vessel rupture.

Environmental Chambers: Protecting sensitive biological or electronic samples from accidental freezing or overheating.

Plastic Processing: Preventing material degradation and fire in heated manifolds and hot runner systems.

Installation and Maintenance

Installation

Panel Cutout: Fits a standard 1/8 DIN vertical cutout ($45mm \times 92mm$).

Sensor Placement: The Type J thermocouple for this limit must be placed as close to the heat source as possible, typically separate from the control sensor.

Power Wiring: Ensure the 120/240V selector switch (if applicable) is set correctly before applying power to avoid blowing the internal transformer.

Maintenance

Limit Testing: It is best practice to “test-trip” the limit monthly by lowering the setpoint below the current temperature to ensure the relay mechanically clicks and breaks the circuit.

Terminal Tightening: Vibration can loosen screws over time; check connections annually to prevent “nuisance trips” caused by high-resistance sensor readings.

Clean Contacts: If switching high-current loads directly, inspect the relay life cycle status; however, it is recommended to use the 997 to drive a larger contactor.

Other Models in the Same Series

The SERIES 997 was often customized by input type and output configuration:

As the SERIES 997 is a legacy product, many users are now migrating to the modern Watlow PM6 (EZ-ZONE®) series for digital networking capabilities.

However, the 997D remains a staple in existing panels due to its rugged reliability.

PM6L: The modern replacement for the 997. offering Bluetooth® connectivity and improved accuracy.

1/8 DIN Adapters: Available if you are upgrading from a vertical 997 to a horizontal controller.