Omron G9SA-321-T30 Safety Relay Unit

Technical Overview

DIN rail safety relay with 30s adjustable OFF-delay. Features 3PST-NO main, DPST-NO delayed, and SPST-NC aux contacts. PLe/Cat 4 compliant for advanced safety.

Key Features

Provides 3PST-NO instantaneous safety outputs and DPST-NO OFF-delayed safety outputs [1.1.3].
Configurable 15-step OFF-delay timer settings up to 30 seconds.
Supports dual-channel and single-channel safety inputs for system versatility.
Conforms to EN ISO 13849-1 (PLe/Safety Category 4 for instantaneous contacts, Category 3 for OFF-delayed contacts).
Dual installation capability supporting both DIN track mounting and screw mounting.
Simple expansion connection interface allows front-coupling with G9SA Expansion Units.
Auxiliary contact (SPST-NC) provides instant status feedback to PLC monitoring systems.

Technical Specification Matrix

Parameter	Value
Contact Configuration (Instantaneous)	3PST-NO
Contact Configuration (OFF-delayed)	DPST-NO
Contact Configuration (Auxiliary)	SPST-NC
Off-Delay Settings	2s, 4s, 6s, 8s, 10s, 12s, 14s, 16s, 18s, 20s, 22s, 24s, 26s, 28s, 30s (15 steps) [1.1.3]
Rated Voltage Options	24 VAC/VDC or 100 to 240 VAC
Operating Voltage Range	85% to 110% of rated voltage
Input Current	40 mA max.
Rated Load (Resistive)	250 VAC, 5 A or 30 VDC, 5 A
Rated Carry Current	5 A
Power Consumption (24 VAC/VDC)	8.6 VA / 3.3 W max.
Power Consumption (100 to 240 VAC)	12.5 VA max.
Contact Resistance	100 mΩ max.
Operating Time	30 ms max.
Response Time	10 ms max.
Dielectric Strength	2,500 VAC, 50/60 Hz for 1 min (between input and output)
Insulation Resistance	100 MΩ min. (at 500 VDC)
Ambient Operating Temperature	-25°C to +55°C (no icing or condensation)
Ambient Operating Humidity	35% to 85% RH
Terminal Tightening Torque	0.6 N·m
Vibration Resistance	10 to 55 to 10 Hz, 0.375-mm single amplitude
Shock Resistance (Destruction)	300 m/s²
Physical Weight (kg)	0.27
Dimensions L x W x H (cm)	11.1 x 4.5 x 7.6

Industrial Applications

1. Controlled Deceleration of High-Inertia Industrial Centrifuges

In high-inertia rotating systems like heavy centrifuges, instantly cutting off drive power during an E-stop can cause mechanical failure or operator hazards. The relay initiates an immediate stop to the primary motor controller using the instantaneous 3PST-NO contacts, while the DPST-NO OFF-delayed contacts (set up to 30 seconds) maintain lock control on the enclosure doors until residual spin-down energy safely dissipates [1.1.3].

Problem Solved

Prevents catastrophic mechanical damage from harsh sudden stops and protects operators from accessing dangerous high-speed rotating elements during the spin-down phase.

Controlled DecelerationOff-Delay Safety ContactHigh-Inertia MachineryGuard LockingE-Stop Safety

2. Multi-Zone Conveyor Cascaded Shutoff and Clearing Sequence

On complex automated packaging and assembly conveyor lines, an emergency stop at one zone can cause pile-ups if all sections stop simultaneously. When an E-stop is triggered, the upstream section is halted instantly using the instantaneous 3PST-NO safety contacts, while the downstream conveyor continues running for a configured delay (via the DPST-NO OFF-delayed contacts) to clear out product in transit before fully shutting down the entire system.

Problem Solved

Avoids material jams, packaging collisions, and structural overload on multi-zone conveyor systems during emergency shutdowns.

Conveyor InterlockingCascaded Stop SequenceMaterial Jam PreventionDual-Channel Safety InputCategory 4 Safety

3. Robotic Welding Cell Enclosure Guard Lock Access Delay

Robotic welding cells present residual hazards even after a stop command, such as active high-temperature welding tips and toxic shielding gases/fumes. Operating the guard door's solenoid latch via the DPST-NO OFF-delayed safety contacts ensures that the cell remains physically locked for a precise delay (e.g., 20 seconds) after the robot is deactivated, ensuring air exhaust systems clean the air and welding tips cool down.

Problem Solved

Protects industrial operators from contact with hot workpiece zones and exposure to toxic post-process fumes inside the robotic workspace.

Solenoid InterlockGuard Lock AccessRobotic Cell SafetyFume Dissipation DelayCategory 3 OFF-Delay