Eaton 821-DC-TC Programmable Relay

Description

Eaton 821-DC-TC Programmable Relay

The Eaton EASY821-DC-TC (often listed as 821-DC-TC) is an advanced intelligent programmable relay from Eaton’s popular easy800 control relay series. It bridges the gap between simple control relays and full-scale PLCs, offering powerful control and communication logic in a compact, DIN-rail mounted module.

Product Detailed Description

The EASY821-DC-TC is designed for small to medium-sized automation tasks. The model name itself reveals its core hardware configuration:

• 800 Series: Provides advanced programming functionality, including calculation functions, PID controllers, and network networking (easyNet).
• DC: Operates on a 24 V DC power supply.
• TC: Outfitted with Transistor (T) outputs and features a built-in Clock (C) for time-dependent switching operations.

Technical Parameters

Product Advantages

• Built-in easyNet: Enables local, low-cost distributed networking. Up to 8 modules can communicate with each other over a distance of up to 1000 meters, allowing them to share I/O statuses and data effortlessly.
• High-Speed Outputs (Transistor): Unlike relay outputs which suffer from mechanical wear and slower response times, transistor outputs allow for rapid, arc-free switching and support Pulse Width Modulation (PWM) or high-frequency pulses.
• Hybrid Inputs: The flexibility to use 4 inputs as either standard digital or 0-10V analog inputs saves space and reduces the cost of buying specialized analog expansion modules.
• Advanced Function Blocks: Packed with rich software functions, including PID controllers, high-speed counters (5 kHz), arithmetic blocks, and multi-level text displays.

Important Considerations & Precautions

• Output Current Limit: Transistor outputs are rated for a maximum of 0.5 A. Attempting to drive high-current inductive loads (such as large contactors or motors) directly will destroy the output transistors. Always use external interposing relays for heavy loads.
• Polarity Protection: Ensure the 24 V DC power supply is wired with correct polarity. Reverse polarity can damage the unit’s logic circuitry.
• Programming Software: While basic modifications can be made via the hardware buttons on display-equipped models, comprehensive system logic should be configured using Eaton’s easySoft-Pro software.
• Inductive Kickback: When switching inductive DC loads (like small solenoids), always connect a flywheel/freewheeling diode in parallel with the load to absorb voltage spikes.

Product Applications

The EASY821-DC-TC is highly versatile and frequently utilized across multiple industries:

• Machine Building (OEM): Controlling packaging machines, conveyor routing systems, and specialized cutting or printing equipment.
• Building Automation: Managing lighting controls, shutter/blind automation, heating/ventilation tracking, and greenhouse climate controls.
• Pumping & Environmental: Automating small wastewater pumping stations, level control in multi-tank systems, and automated irrigation.
• Decentralized Subsystems: Functioning as a smart remote I/O node in a larger industrial network, processing local data before sending it to an overarching master PLC or DCS.

Shipping Port: Xiamen, China

Payment: Bank of Chicago, Bank of Singapore

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