Industrial-Grade Freeze Protection for Mission-Critical Cooling Loops

Industry Information

• Industry: Multiple Industrial Industries
• Plant Type: Cooling Systems
• Project Type: Primary Cooling Infrastructure & Chilled Water Lines
• Scope: Freeze Protection Control

Application

In data center environments, uninterrupted cooling is paramount to preventing thermal runaway in high-density server racks. Large-scale chilled water systems are engineered to handle these immense, continuous heat loads; however, rapid load fluctuations or drops in fluid velocity can cause outdoor chiller evaporators and exposed external piping loops to plummet in temperature, risking catastrophic tube ruptures due to water expansion. To safeguard these critical assets, the Yokogawa UT35A digital indicating controller provides a robust, dual-layered freeze mitigation solution deployed directly at the chiller units and outdoor hydronic lines. By continuously monitoring low-bound process variables via high-accuracy RTDs or thermocouples on evaporator barrels and exposed piping skins, the UT35A serves as a dependable fail-safe.

Executive Summary

What sets the UT35A apart in high-availability data center applications is its integrated Heater Break Alarm (HBA) capability, which transforms passive freeze protection into an active, self-diagnostic system. Using a direct-current transformer (CT) input, the controller continuously verifies the electrical integrity of backup heating circuits and immediately detects element burnouts, tripped breakers, or short-circuited solid-state relays. This proactive monitoring ensures that the freeze-mitigation system is fully operational long before an environmental freezing hazard occurs. By seamlessly routing diagnostics to Building Management Systems (BMS) and Data Center Infrastructure Management (DCIM) platforms, the UT35A minimizes the risk of catastrophic hardware damage while protecting business continuity.

Solution

1. Precision Temperature Control

• Responsive thermal tracking using dynamic PID control.
• Direct connection to dual-element RTD or thermocouple sensors.
• Continuous monitoring of critical heat exchanger surfaces and pipe walls.

2. Freeze-Protection Logic and Advanced Alarming

• Automatic transition from monitoring to active freeze prevention.
• Interlocks, permissive logic, and output adjustments as conditions require.
• Dual outputs and visual alerts for heat-trace activation and bypass valve operation.

3. Simplified Local Control Architecture

• Single-unit execution combining sequence control and PID tuning.
• Built-in ladder logic for advanced local automation.
• Native Modbus/TCP and BACnet integration with building management systems.

Products Used

UTAdvanced Industrial Controllers

• Advanced PID control, ladder sequence control, and fuzzy logic
• Function block programming
• Bright color LCD displays with scrolling text
• Ethernet, Modbus, PROFIBUS, CC-Link, and DeviceNet communications
• NEMA 4 faceplate

Customer Quote

"What made this solution valuable was not just the controller itself, but the complete packaged approach. The integrated controller, CT, RTD, and wiring created a plug-in heat trace control kit that helped us reduce installation complexity, verify system operation, and keep pace with high-volume production demand."

— Thermal Systems Engineer at an Original Equipment Manufacturer (OEM) specializing in design, simulation, and optimization of water-cooled and air-cooled chiller systems for data center deployments.