Top Uses for Overload Relays in HVAC and Motor Protection

Overload relays are a frontline defense that often determines whether a system survives an unexpected fault or ends up in costly downtime. In HVAC and industrial motor applications, sustained overloads, phase loss, or locked rotor conditions can burn out windings in minutes. 

The reality: many breakdowns occur not because the motor was weak, but because the protection strategy wasn’t precise enough for the load profile. Selecting the correct overload relay matched to voltage, amperage, and trip class is an operational insurance policy.

Why Overload Relays Matter from the Start

• Targeted motor protection: By monitoring current and heat, overload relays shield motors from sustained overloads, especially critical in HVAC compressors and industrial ventilation systems.

• Cost-effective safety: They offer precise protection for a relatively low investment, especially compared to integrated motor protection devices.

• Complementary design: When paired with contactors or breakers, overload relays become part of a layered protection strategy, addressing different risk types like short circuits, thermal stress, and phase failure.

Key Applications for Overload Relays

1. HVAC Compressors & Pumps

In cooling and heating systems, compressors can experience long startup currents or mechanical lock-ups. Overload relays prevent winding damage by responding to sustained overcurrents and allowing normal inrush currents.

2. Motor Control Centers (MCC) & Starters

Within MCCs, overload relays are typically paired with contactors as part of magnetic starters. They disconnect the control circuit when overload occurs, stopping the motor safely.

3. Industrial HVAC & Blower Motors

Large fans and blowers are subject to varying loads and voltage anomalies. Overload relays detect overload conditions and phase imbalance, preventing overheating and unplanned downtime.

4. Refrigeration Systems

Overloads can stress compressors in chillers and refrigeration units. Overload relays help prevent electrical or mechanical damage by promptly disconnecting power during overloads.

5. Compact Motor Installations

In installations where space is constrained—such as compact control panels—dense, reliable overload relays ensure motor safety without bulky equipment.

6. Broad Industrial Scenarios

Across manufacturing facilities, water treatment, and HVAC installations, overload relays safeguard valuable equipment by minimizing repair costs and preventing collateral damage.

Types, Features & Selection Criteria

Types of Overload Relays:

• Thermal (bimetallic): Uses heat-induced movement to trip. Inexpensive and suitable for simple applications.

• Electronic (solid-state): Offers precision, ambient compensation, adjustable trip classes, and often diagnostic capabilities.

Key Features to Consider:

• Trip Class (10, 20, 30…): Determines how quickly the relay trips under overload; select based on motor type and inertia.

• Reset Type: Automatic vs. manual impacts how the system responds after a trip. Automatic resets can reduce downtime; manual resets offer safer troubleshooting.

• Environmental Resilience: Ensure relays can withstand ambient heat, humidity, and vibration, especially in HVAC or industrial settings.

• Auxiliary Contacts & Signaling: Useful for connecting alarms or PLC signals to monitor trips. Modern setups often leverage these for proactive maintenance.

Recommended Products Available at Voomi Supply

Here are five carefully selected overload relay solutions, sourced from some of the top industry brands. Each offers unique benefits in the contexts of motor and HVAC protection.

CAPTIVEAIRE Motor Overload 193-KB40

• Voltage versatility: Supports AC (24, 240, 400, 690 V) and DC (24, 110, 220, 440 V).

• Built to last: Durable plastic casing with trip indicator and phase-loss sensitivity.

• Benefits: Ideal when you need one relay compatible across diverse voltage systems, especially in HVAC, where both AC and DC controls may coexist.

Eaton AN16GN0BB NEMA Freedom Series (Non-Reversing Reset)

• Wide motor horsepower range: 3 hp @ 115 V up to 15 hp @ 240 V (and up to 25 hp @ 480/600 V).

• Robust design: 45 A, 3-pole, UL/CSA certified; fits well in OEM panels.

• Benefits: Perfect for industrial and panelbuilder applications needing reliable thermal overload protection and global certification.

Copeland 971-0554-22 Overload Relay

• Adjustable trip: 20–60 A range, with manual/automatic reset.

• Compact footprint (under 3 inches) and light.

• Benefits: Tailored for refrigeration and HVAC compressors. Its adaptability makes it a great safety safeguard in tight spaces.

Schneider Electric LR2K0316 Terminal Relay

• Thermal range: 8-11.5 A with trip class 10; designed for 4 kW motors at 400 V.

• Operational flexibility: Manual or automatic reset; includes 1NO+1NC auxiliary contacts.

• Benefits: Mounts directly on TeSys K contactors, offering phase unbalance protection. It’s an excellent choice for industrial motors requiring both reliability and IEC/UL/CSA certification.

Tecumseh K90-23 Overload Relay

• Purpose-built: Designed for HVAC and refrigeration compressors.

• Compact and dependable: Lightweight yet robust for continuous operation.

• Benefits: Genuine Tecumseh part ensures proper fit and reliable overload protection. It’s ideal for refrigeration techs looking to maintain OEM performance standards.

Why Voomi Supply Stands Out in Supplying Overload Relays

At Voomi Supply, our mission is to streamline your procurement experience with:

• One-stop convenience: You can choose HVAC, plumbing, or electrical components, especially hard-to-find overload relays, and you’ll find what you need fast.

• Expert-curated options: The models above represent reliable, high-performance solutions from trusted brands like CAPTIVEAIRE, Eaton, and Copeland.

• Dependable delivery: Our logistics ensure your components arrive rapidly, so installation downtime is minimized.

• Industry insight: We go beyond product listing and provide you with not just equipment, but the know-how to integrate them effectively.

Key Takeaways on Overload Relays

In this guide, we explored how overload relays are indispensable in protecting motors, compressors, and electrical equipment across HVAC and industrial settings. Key insights include:

• Targeted motor defense: They detect overheating from sustained overloads, prolonging motor life and preventing system downtime.

• Versatile applications: From refrigeration compressors to motor control centers in factories, overload relays offer critical protection.

• Smart selection matters: Choose between thermal and electronic types, match trip class, reset type, and certifications to your environment.

With Voomi Supply, you get expert guidance, unmatched product selection, and trust-based service. This all comes from a single source.

Safeguarding your motors means smart choices with quality components. Ensure your systems run safely, efficiently, and with peace of mind using reliable overload relay solutions.