Purchase now: Allen Bradley 1746-IM16 AC Input Module
Purchase now: Atlantechdrives provides you the 1746-IM16, a heavy-duty, high-voltage digital input module designed by Allen Bradley for the renowned SLC 500 automation control system. This specific module features 16 input points and is engineered to operate on a 220/240V AC power configuration. It is the perfect solution for industrial facilities, power plants, and manufacturing floors that utilize high-voltage control circuits. By allowing the SLC 500 processor to directly read the status of 220V AC limit switches, motor starter auxiliary contacts, and relay panels, the 1746-IM16 eliminates the need for intermediate step-down transformers or external interposing relays, simplifying panel wiring and reducing potential failure points.
Technical Specifications of the 1746-IM16
Built for the harshest industrial environments, the 1746-IM16 provides excellent optical isolation, protecting the sensitive 5V DC backplane of the PLC from the harsh 220V AC field voltages. The 16 inputs are typically grouped to share common terminals, streamlining the wiring process within the control cabinet while ensuring maximum operational safety.
- Part Number: 1746-IM16
- Module Type: Digital AC Input Module
- Compatible System: SLC 500 Programmable Logic Controllers (1746 Series)
- Number of Inputs: 16 Points
- Voltage Category: 220 / 240V AC
- Operating Voltage Range: 170…265V AC (47…63 Hz)
- Maximum Inrush Current: 1.6 mA
- Signal Delay (Max): On: 35 ms, Off: 45 ms
- Backplane Current Draw: 85 mA at 5V DC
- Isolation: 1500V AC dielectric withstand
Expert Tips: Managing AC Input Leakage Current
When working with 220V AC input modules, «ghost» or «phantom» voltages are a frequent troubleshooting challenge. Expert Tip: Many modern field devices, such as solid-state proximity sensors or switches with built-in neon indicator lights, allow a small amount of leakage current to pass through even when they are in the «OFF» state. Because the 1746-IM16 is highly sensitive, this leakage current might be enough to keep the input registered as «ON» in the PLC logic, even when the switch is physically open. If you experience inputs that refuse to turn off, you must install a burden resistor (bleeder resistor) in parallel with the module’s input terminal and the AC common to bleed off the excess leakage current and pull the voltage below the module’s true OFF threshold.
Maintenance and Heat Dissipation
Operating at 220/240V AC inherently generates more internal heat than low-voltage DC applications. Ensure that your SLC 500 chassis is adequately ventilated and free from obstructions. When routing wires to the removable terminal block, ensure that no copper strands are exposed, as 220V AC poses a significant arcing and safety hazard. Periodically retorque the terminal screws to prevent loose connections caused by standard machine vibration, which could lead to micro-arcing and terminal damage over time.
Frequently Asked Questions (FAQs)
Q: Can I install the 1746-IM16 next to a DC input module in the same chassis?
A: Yes, the SLC 500 chassis allows you to mix AC and DC modules. However, you must ensure that the high-voltage AC field wires are routed completely separately from the low-voltage DC wires inside your control panel to prevent electrical noise induction.
Q: Does this module require a specific removable terminal block (RTB)?
A: Yes, like most high-density 16-point SLC modules, it utilizes a removable wiring arm to connect the field wiring to the front of the card. This allows you to replace a damaged module without rewiring the entire rack.
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