SICK RLY3-EMSS300 Safety Relay Manual

SICK RLY3-EMSS300 Safety Relay Configuration and Troubleshooting Guide

In the machine safety protection system, safety relays play a key role as evaluation units in connecting sensors and actuators to ensure reliable shutdown of hazardous states. The RLY3-EMSS300 launched by SICK is a compact (18mm width) safety relay designed specifically for safety sensors with passive contact outputs. It can reach up to SIL 3 (IEC 61508), Cat. 4, and PL e (ISO 13849-1), with a hazard failure rate PFHp as low as 1.0 × 10 ⁻⁹ per hour and a mission time of 20 years. This device has 3 forced guided safety output contacts, 2 diagnostic outputs, 3 test pulse outputs, and supports functions such as external device monitoring (EDM), reset interlock, differential monitoring, and cross circuit detection. This article will provide a detailed discussion on the technical parameters, safety features, wiring configuration, typical applications, and troubleshooting of RLY3-EMSS300, providing a practical guide for automation engineers to refer to directly.

Product Overview and Core Application Scenarios

RLY3-EMSS300 belongs to the SICK ReLy series of safety relays, designed to provide a high-performance evaluation platform for electromechanical safety switches such as safety door switches, emergency stop buttons, dual hand control boxes, safety touchpoints, etc. Unlike complex safety PLCs that require software parameterization, this device adopts a hard wired configuration, where all functions are implemented through terminal connections without programming, making it ideal for scenarios that require high debugging speed and on-site maintainability.

Typical applications include:

Monitoring of emergency stop button (single channel or dual channel)

Monitoring of protective door switches (with or without locking function)

Output evaluation of safety light curtains/gratings (via passive contacts)

Monitoring of safety carpets or safety edges

Evaluation of Two Hand Operated Control Boxes (Compliant with EN 574)

As a safety signal relay for higher-level control systems

This device complies with stop category 0 (IEC 60204-1), which means that the actuator power is immediately cut off without delay upon safety triggering.

Detailed technical specification interpretation

2.1 Safety parameters

Meaning of parameter values

SIL 3 is suitable for applications with the highest safety integrity level

Category 4 conforms to the highest structural category of ISO 13849-1

PL e performance level highest level

PFHp 1.0 × 10 ⁻⁹ has an extremely low hazard failure rate per hour and is suitable for high demand mode

TM has a 20-year mission duration, during which the safety parameters are valid

Stop category 0 and immediately cut off the power supply

This PFHp value means that only one hazardous failure may occur every one billion working hours, which is a very high level of safety in the field of industrial automation and can meet the highest safety requirements for automotive manufacturing, stamping equipment, robot workstations, and more.

2.2 Power Supply and Environment

Supply voltage: 24 V DC (PELV or SELV), allowable range 16.8 V... 30 V, residual ripple ≤ 2.4 V

Power consumption: ≤ 2.5 W

Working temperature: -25 ℃...+55 ℃, storage temperature: -25 ℃...+70 ℃

Protection level: IP20 (to be installed inside the control cabinet)

Humidity: ≤ 95%, no condensation

Engineers should be aware that this equipment is not suitable for outdoor or humid dusty environments and must be installed in cabinets that meet IP54 or higher standards.

2.3 Input Characteristics

The device provides the following input terminals:

2-channel secure input (S1, S2)

Adaptive sensor type: Safety sensors with potential isolated passive contacts (such as NC contacts for emergency stop buttons, NC/NO contacts for safety door switches)

High level threshold: 24 V DC (11 V... 30 V)

Low level threshold: 0 V DC (-3 V... 5 V)

Input current: 4 mA... 6 mA

Tolerance time between two start buttons: ≤ 3 seconds (for dual hand operation synchronous monitoring)

1-channel reset/EDM input (X1)

Function can be configured as: manual reset button input or external device monitoring feedback signal input

Electrical parameters are the same as safety inputs

3-channel test pulse output (T1, T2, T3)

Type: PNP semiconductor output, short circuit protection

Output voltage: ≥ Vd-3 V

Test pulse width: 2 ms

Test pulse interval: 40 ms

Function: Provide pulsed power supply for external safety sensors (such as safety carpets and light curtains) to detect cross circuit and short circuit faults

2.4 Output Characteristics

3 safety enable current paths (13-14, 23-24, 33-34)

Contact type: Positive guided N/O contact

Contact material: Silver alloy, gold-plated (suitable for low-level signals)

Switching voltage range: 10 V AC... 230 V AC/10 V DC... 230 V DC

Switching current range: 10 mA... 6 A (AC/DC universal)

Total current capacity: 12 A (sum of three contacts?)? The original text "Total current 12 A" should be understood as the maximum total current carried by all contacts simultaneously, with a maximum of 6 A per contact in reality

Mechanical lifespan: 1 × 10 ⁷ switching cycles

Overvoltage category: III (EN 60664-1)