The **JR28-R-DLFP1** (often associated with the Chint or generic IEC-standard series) is a thermal overload relay designed specifically for electrical motor protection. It is typically used in conjunction with a magnetic contactor to form a motor starter. --- ## 1. Technical Specifications Below are the primary electronic and electromechanical specifications for this component: | Specification | Details | | :--- | :--- | | **Component Type** | Thermal Overload Relay | | **Thermal Protection Range** | Adjustable (Typically 0.1A to 630A depending on specific sub-model) | | **Control Voltage** | Usually 220V - 690V AC | | **Auxiliary Contacts** | 1 NO (Normally Open) + 1 NC (Normally Closed) | | **Tripping Class** | 10A (Standard motor protection) | | **Mounting** | Direct plug-in to contactor or independent DIN rail mounting | --- ## 2. Key Internal Components The JR28-R series operates on electromechanical principles rather than purely digital electronics. Its "electronic" behavior is governed by the following parts: ### A. Bimetallic Strips These are the primary sensing elements. When the motor draws excessive current, these strips heat up. Because they consist of two metals with different expansion rates, they bend when heated, eventually triggering the internal trip mechanism. ### B. Differential Mechanism (Phase Failure Protection) The "R" in the series often signifies high-reliability features like phase failure protection. This is a mechanical differential slide that detects if one phase is missing or unbalanced, causing the relay to trip faster than a standard overload. ### C. Auxiliary Contacts (95-96 / 97-98) * **NC (95-96):** Wired in series with the contactor coil to cut power when a fault is detected. * **NO (97-98):** Used for signaling or alarm circuits to notify a PLC or operator of a trip. --- ## 3. Control Interface The front face of the device includes several user-adjustable components: 1. **Current Setting Dial:** A rotary potentiometer-style dial used to match the relay's trip point to the motor's Full Load Amps (FLA). 2. **Reset Button:** A blue button that allows for **Manual** or **Auto** reset modes. 3. **Test/Stop Button:** A red button used to manually simulate a trip or test the auxiliary contact functionality. 4. **Trip Indicator:** A mechanical flag that pops out to show the device has been triggered. --- ## 4. Wiring Diagram Representation In a standard circuit, the wiring follows this logic: ```mermaid graph TD A[L1, L2, L3 Power] --> B[Magnetic Contactor] B --> C[JR28 Thermal Relay] C --> D[Motor] C -.-> E[Control Circuit/NC Contact] E --> B ``` ---