Qualitrol 118P-120-K-0-2 Temperature Monitor

Qualitrol 118P-120-K-0-2 Electronic Temperature Monitor for Dry-Type Transformers

The Qualitrol 118P-120-K-0-2 is a microprocessor-based Intelligent Transformer Monitor (ITM) engineered specifically to protect dry-type distribution, propulsion, and auxiliary step-down transformers. In demanding environments—such as commercial marine engine rooms, offshore drilling rigs, and heavy utility substations—unmonitored core and winding heat soak causes catastrophic insulation dielectric breakdown.

The 118P-120-K-0-2 resolves this by continuously reading up to three independent Type K (Chromel-Alumel) thermocouples embedded directly into the low-voltage and high-voltage phase coils. The monitor executes precise multistage cooling fan automation, progressive thermal alarm warnings, and emergency breaker trip actuation. Equipped with a high-contrast front-panel digital LED display and diagnostic indicator lamps, the unit delivers instantaneous thermal visibility while retaining the highest recorded phase temperature for post-trip forensic analysis.

Model Details

• Manufacturer: Qualitrol Company LLC
• Product Series: 118 / 118P / 118 ITM Series
• Model Number: 118P-120-K-0-2
• Manufacturer Part Number (MPN): 118P120K02
• Internal / Assembly Reference: TMDS243313

Technical Specifications

Key Features

1. Three-Phase Thermal Scanning: Dedicated acquisition for three Type K thermocouples continuously calculates and displays individual winding hot-spot profiles and stores absolute peak operating values.
2. Multistage Relay Actuation: Heavy-duty electromechanical dry contacts configured for automatic forced-air fan control, high-temperature pre-alarms, and failsafe high-high emergency trip signaling.
3. Automated Fan Exerciser: Built-in programmable timing cycle periodically rotates cooling fans during extended low-load periods, preventing motor bearing freeze, grease gumming, and dust buildup.
4. Sensor Diagnostics & Open-Circuit Detection: Built-in burnout protection triggers a non-trip alarm and front-panel open circuit indicator (“—“) if a thermocouple lead severs or drifts, avoiding false transformer tripping.
5. Rugged Steel Flush Mount Architecture: Industrial vibration-resistant enclosure with heavy-gauge terminal strips engineered to withstand harsh high-EMF, marine switchboard, and switchgear installations.

Equipment Compatibility

• Switchgear & Transformer Manufacturers: Square D / Schneider Electric (Sorgel series), ABB / Hitachi Energy, Siemens (GEAFOL and 3AH/ADVAC switchgear line), Eaton / Cutler-Hammer, Hammond Power Solutions (HPS), and Federal Pacific.
• Marine & Offshore Power Plants: Main Propulsion step-down transformers, bow thruster step-up units, 440V distribution skids, and emergency switchboard enclosures.
• Industrial Drive Isolation: Variable Frequency Drive (VFD) 6-pulse, 12-pulse, and 24-pulse dry-type isolation transformers.

Applications

• Marine Vessel Machinery Spaces: Continuous thermal oversight of propulsion step-down transformers, vessel service transformer banks, and deck winch power skids exposed to severe engine room ambient heat.
• Offshore Oil & Gas Platforms: Topside hazard-mitigated electrical rooms where continuous fan automation is vital to keep switchgear rooms pressurized and cool.
• Commercial & Utility Substations: Indoor cast-resin and vacuum pressure impregnated (VPI) transformers in hospitals, data centers, high-rise buildings, and underground metro tunnels.
• Renewable Power Installations: Inverter-duty step-up transformers in wind turbine nacelles/towers and commercial solar field distribution hubs.

Frequently Asked Questions

What does error code “—” mean on the Qualitrol 118P digital display?

The “—” readout indicates an open-circuit sensor fault. The monitor has detected a severed wire, missing thermocouple, or damaged probe on that specific channel. The alarm relay triggers to notify technicians, but the trip relay remains inactive to prevent accidental power outages.

Can the Qualitrol 118P-120-K-0-2 accept RTD sensors like PT100?

No. The “K” in the model designation indicates that the internal analog-to-digital converter board and terminal cold-junction block are factory-hardware calibrated exclusively for Type K thermocouples. For 100-ohm platinum RTDs, a dedicated Qualitrol 118 unit calibrated for RTD inputs must be specified.

What is the difference between 118P-120-K-0-2 and 118P-120-K-4-2?

The numerical suffix specifies relay configuration and hardware I/O options. The “0-2” variant features standard dry contact arrangements (Fan, Alarm, Trip), whereas “4-2” configurations often include extra auxiliary form-C contacts (Relay 4 and Relay 5) or dedicated remote SCADA output loops.

How do I test the fan and alarm relays without taking the transformer offline?

The unit features an integrated front-panel test button routine. Pressing and holding the test interface cycles the LED segments, audits internal setpoint thresholds, triggers the audible beeper, and allows controlled verification of output relay contacts without applying real physical heat to the transformer winding sensors.

What power supply can be wired to the primary input terminals?

The 118P-120-K-0-2 uses a nominal 120 VAC auxiliary line, but incorporates an internal universal power supply stage capable of safely handling operational fluctuations between 80 to 300 VAC (50/60 Hz) or 48 to 280 VDC.