JR28 Thermal Overload Relay

Safeguard your motors with the JR28 Thermal Overload Relay, a robust and intelligent protection solution developed by CDADA, a reliable manufacturer in China. Designed for seamless integration with CDADA D-series contactors (D9 to D150), the JR28 relay provides comprehensive defense against:

● Overloads

● Phase failure (loss of one phase)

● Excessively long motor starting times

● Prolonged rotor stalling

With an extensive adjustable current range from 0.1A up to 140A, the JR28 series covers applications from small fans to large industrial pumps and compressors. It features a test button for control circuit verification, a clear trip indicator, manual or automatic reset selection, and a sealable cover to prevent unauthorized adjustments. Built on proven bimetallic thermal technology and compliant with IEC 60947-4-1, the CDADA JR28 ensures reliable, maintenance-friendly motor protection in demanding environments worldwide.

Key Specifications

Series: JR28 Thermal Overload Relay

Brand: CDADA | Manufacturer: Shanghai DADA Electric CO.,LTD

Compatibility: Designed for D9, D12, D18 … up to D150 contactors (LC1-D/F series)

Rated Current Range: 0.1A – 140A (multiple models: JR28-25, JR28-36, JR28-93, JR28-150, etc.)

Poles: 3-pole (monitors all phases for imbalance)

Protection Functions:

★ Thermal overload

★ Phase failure detection

★ Long start time monitoring

★ Rotor stall protection

Reset Mode: Manual or Automatic (via selector switch)

Test Button: Simulates trip—activates both NO and NC auxiliary contacts

Stop Button: Opens NC contact only (for emergency signaling)

Trip Indicator: Visual flag shows tripped status

Setting Lock: Cover can be sealed for tamper-proof operation

Auxiliary Contacts: Standard 1NO + 1NC (for alarms, PLC feedback, or interlocks)

Mounting: Snap-on design directly onto compatible CDADA contactors

Certification: Compliant with IEC/EN 60947-4-1 (CE documentation available)

Why Choose CDADA JR28 Thermal Overload Relay?

★  Wide Current Coverage

From 0.1A to 140A—supports everything from fractional HP motors to 110kW+ industrial drives.

★ Full Compatibility with D-Series Contactors

Engineered to fit D9 through D150—ensures perfect mechanical and thermal coordination.

★ Advanced Diagnostic Features

★ TEST button verifies control wiring without power interruption

★ STOP button enables external signaling

★ Trip indicator speeds up troubleshooting

★ Industrial-Grade Reliability

True bimetallic thermal mechanism (not electronic)—immune to EMI, voltage spikes, and software faults.

★ Safety & Compliance Ready

Sealable cover meets ISO, CE, and factory audit requirements for locked settings.

★ Cost-Effective Protection

Prevents motor burnout, reduces downtime, and extends equipment life—ideal for OEMs and system integrators.

★ Packing details vary by product. We provide this information in our quotations and packing lists. Standard export cartons are designed for optimal palletization and container loading.

Typical Applications

★ Motor Starter Assemblies: Paired with contactors for pumps, fans, conveyors

★ HVAC Systems: Chillers, cooling towers, air handlers

★ Water & Wastewater: Submersible and centrifugal pumps

★ Manufacturing: Mixers, extruders, packaging lines

★ Mining & Construction: Crushers, hoists, ventilation fans

Frequently Asked Questions

Q1: What’s the difference between JR28 and LRD series?

A1: Both are thermal overload relays from CDADA. The JR28 series supports higher currents (up to 140A) and is designed for larger contactors (up to D150), while LRD typically covers lower ranges (up to ～104A). Functionally, they offer similar protection—but JR28 is optimized for heavy-duty industrial use.

Q2: Can I use JR28 Thermal Overload Relay with non-CDADA contactors?

A2: While possible in some cases, optimal performance and warranty support require pairing with CDADA D-series contactors (D9–D150). Mechanical fit, heat dissipation, and coordination curves are validated as a system.

Q3: How does phase failure protection work in JR28?

A3: If one phase is lost, the remaining two conductors carry unbalanced current, causing asymmetric heating in the bimetallic strips. The JR28 detects this imbalance and trips faster than under normal overload, preventing motor winding damage.

Q4: Is manual reset safer than auto reset?

A4: Yes—for critical systems. Manual reset forces an operator to inspect and clear the fault before restarting. Auto reset is suitable for unattended or remote equipment where continuity is prioritized (e.g., cooling pumps).

Q5: Why choose CDADA JR28 over global brands?

A5: CDADA offers:

● True thermal differential mechanism with high accuracy

● Full compatibility with D9–D150 contactors—plug-and-play reliability

● Test, stop, reset, and seal functions in one compact unit

● Competitive pricing with CE-compliant quality

● Fast technical support and English documentation for global customers