Overview
The Crydom D4840 is a single-phase solid state relay designed for demanding industrial switching applications. It is a panel-mount solid-state relay designed for heavy industrial applications, featuring SCR output for reliable high current switching. With a control input range of 3–32VDC and an output rating of 40A @ 480VAC, the D4840 provides efficient on/off control for AC loads including motors, heating elements, and inductive equipment.
Key Features
- Zero voltage (resistive loads) or random-fire (inductive loads) output
- Sturdy housing rated for 94V-0 with anti-rotation barriers, aluminum baseplate, and enhanced SEMS screw and washer for secure installation
- Dielectric strength of 4000 VRMS at 50/60Hz between input, output, and base, with at least 10¹ Ω insulation resistance at 500V DC
- Panel-mount design with screw terminals
- RoHS compliant design with durable epoxy-free construction
- SPST-NO (Single Pole Single Throw, Normally Open) configuration
Technical Specifications
- Control Input Voltage: 3–32VDC
- Output Voltage Rating: 480VAC (max 530VAC)
- Output Current Rating: 40A
- Output Type: SCR (Silicon Controlled Rectifier)
- Switching Mode: Zero-voltage turn-on (resistive) / Random-fire (inductive)
- Contact Configuration: SPST-NO
- Mounting Type: Panel-mount with screw terminals
- Dielectric Strength: 4000 VRMS (50/60 Hz) between input, output, and base
- Insulation Resistance: ≥10¹ Ω at 500V DC
- Housing Rating: 94V-0
- Weight: Approximately 2.6 oz (74 g)
- Frequency: 50/60 Hz
Typical Applications
The Crydom D4840 is commonly used in:
- Motor control and soft-start applications
- Heating element and furnace control
- Industrial machinery automation and sequencing
- HVAC and power distribution switching
- PLC-based control systems requiring high current AC switching
- Food processing and packaging automation
Compatibility & Replacements
Compatible With
- PLC systems requiring DC-controlled AC loads (up to 40A)
- 24VDC control outputs from industrial controllers
- Low-voltage DC automation circuits (3–32V)
- Rockwell Automation and Siemens PLC platforms
- Manual industrial control panels with low-voltage logic
Replaces / Drop-In Replacement For
- Crydom Series One solid state relays of equivalent rating
- Sensata D4840 (same part under parent company name)
- Legacy 40A, 480VAC solid state relay installations
Works With
- Industrial control networks and PLC I/O modules
- Standard screw-terminal wiring and industrial panel mounting
- AC load switching applications with 50/60 Hz frequency
- Both resistive and inductive (motor) load control
