The **CB1AF-T-R-24V** is a high-power automotive relay manufactured by Panasonic. It is specifically designed to handle heavy DC loads and survive harsh environments typical of vehicle engine bays or industrial machinery. --- ### 1. Part Number Breakdown Understanding the nomenclature reveals the specific features of this component: | Code | Meaning | Description | | :--- | :--- | :--- | | **CB** | Series | Panasonic CB Series Automotive Relay | | **1A** | Contact Form | 1 Form A (SPST-NO: Single Pole Single Throw, Normally Open) | | **F** | Mounting/Shape | Flux-tight (Standard type) | | **T** | Heat Resistance | High heat resistance (up to 125°C) | | **R** | Suppression | Built-in Resistor for coil surge suppression | | **24V** | Voltage | 24V DC Nominal coil voltage | --- ### 2. Technical Specifications Below are the primary electrical and mechanical characteristics: | Parameter | Specification | | :--- | :--- | | **Nominal Switching Capacity** | 20A at 28V DC | | **Max. Switching Current** | 20A | | **Coil Resistance** | Approx. 320 $\Omega$ (with resistor) | | **Operating Temperature** | -40°C to +125°C | | **Mechanical Life** | Min. $10^6$ operations | | **Contact Material** | AgSnO$_2$ type (Silver Tin Oxide) | --- ### 3. Key Electronic Features #### A. High Heat Resistance ("T" Suffix) Standard automotive relays are often rated for 85°C. The "T" designation indicates this part uses high-grade insulation materials allowing it to function reliably in high-temperature environments, such as near an engine or in heavy industrial equipment. #### B. Resistor for Surge Suppression ("R" Suffix) When a relay coil is de-energized, the collapsing magnetic field creates a high-voltage spike (back EMF). * This model includes an **internal resistor** wired in parallel with the coil. * The resistor dissipates the energy of the spike, protecting sensitive electronic control units (ECUs) or transistors driving the relay from voltage damage. #### C. Contact Arrangement (1 Form A) This is a "Normally Open" relay. The circuit remains broken until the 24V coil is energized, at which point the internal switch closes to power the load. --- ### 4. Typical Applications * **Heavy Duty Vehicles:** Trucks, buses, and construction equipment utilizing 24V electrical systems. * **Engine Components:** Cooling fans, fuel pumps, and glow plugs. * **Industrial Automation:** Actuators and motors requiring 24V DC control.