Allen-Bradley 1692-ZRCLSS 4-Channel Protection Module

The 1692-ZRCLSS is a multi-channel protection device from Rockwell Automation's 1692 series, designed to safeguard PLC input modules from electrical overstress. Each of the four channels combines a varistor (metal oxide varistor) for surge clamping, a series resistor for current limiting, and a capacitor for EMI filtering. The module is typically installed between field devices (sensors, switches) and PLC discrete input cards (e.g., 1746, 1756 series).

Electrical Specifications per Channel

• Nominal Voltage: 24 VDC (12–30 VDC range)

• Clamping Voltage (varistor): 39 VDC (at 1 mA)

• Surge Current Rating: 500 A (8/20 µs waveform) per channel

• Series Resistance: 220 Ω ±5%

• Filter Capacitance: 0.1 µF, 50 V

• Response Time: < 5 ns

Mechanical and Installation

The module measures 45 mm × 75 mm × 55 mm (W × H × D) and weighs 0.1 kg. It snaps onto a 35 mm DIN rail. Each channel uses a 2-pin screw terminal (input from field) and a 2-pin output terminal (to PLC). The module is transparent to normal signal currents up to 50 mA. An LED indicator for each channel shows protection status (green = OK, red = MOV failed).

Protection Scheme

The varistor shunts transient overvoltages (e.g., from inductive load switching or lightning) to ground, limiting the voltage to < 39 V. The series resistor limits current to a safe value (typically < 110 mA at 24 V), preventing damage to optocouplers in the PLC input. The capacitor filters high-frequency noise (common mode and differential mode) up to 30 MHz. Together, the module provides compliance with IEC 61000-4-2 (ESD), 61000-4-4 (burst), and 61000-4-5 (surge) Level 4.

Environmental and Certifications

Operating temperature: -20°C to +60°C; storage: -40°C to +85°C. Humidity: 5–95% non-condensing. The module is UL 508 listed, CSA certified, and CE marked. RoHS compliant. MTBF per MIL-HDBK-217: 800,000 hours.

Typical Applications

Used in systems where PLC input wiring runs long distances (over 30 meters) or near high-EMI equipment (VFDs, contactors). Each channel protects one digital input point. For analog signals, a different module (1692-ANL) is recommended. The 1692-ZRCLSS is especially useful for retrofitting older machinery to improve reliability without changing the PLC.