Siemens 6ES5185-3UA21 ER185U Expansion Rack

Technical Overview

The Siemens 6ES5185-3UA21 is an ER185U expansion rack for the SIMATIC S5 programmable controller series. This chassis extends the I/O capacity of S5-135U and S5-155U systems by providing additional slots for modules. The rack accommodates up to 21 modules in a single expansion unit . A robust cooling fan ensures reliable thermal management, maintaining optimal operating temperatures for installed modules . The Siemens 6ES5185-3UA21 requires a power supply of 24V DC with 5V, 18A capability . Its rack design integrates seamlessly with standard S5 backplane connectors.

Technical Specifications

Parameter	Specification
Manufacturer	Siemens
Model Number	6ES5185-3UA21
Product Type	ER185U Expansion Rack / Chassis
System Compatibility	SIMATIC S5-135U, S5-155U
Number of Slots	21
Power Supply Requirement	24V DC (external); 5V, 18A capability
Cooling	Integrated fan
Dimensions	60 x 43 x 31 cm or 56 x 43 x 55 cm (varies by source)
Weight	10 kg to 19 kg (varies by configuration)
Protection Rating	IP20
Product Phase	Obsolete (since 1994)
Country of Origin	Germany

Key Features

21-Slot Expansion Capacity – The Siemens 6ES5185-3UA21 provides 21 module slots, significantly extending the I/O capacity of S5-135U and S5-155U systems.

Integrated Cooling System – A built-in fan maintains optimal thermal conditions for installed modules, ensuring reliable operation in demanding industrial environments .

Standard S5 Backplane Integration – The rack uses standard S5 backplane connectors for seamless integration with existing S5 automation systems.

Flexible Power Configuration – The chassis requires 24V DC input with 5V, 18A capability, accommodating various power supply configurations .

Robust Industrial Construction – The heavy-duty design withstands harsh industrial conditions, ensuring long-term reliability for legacy system maintenance.

Applications

The Siemens 6ES5185-3UA21 suits expansion applications for SIMATIC S5 systems in manufacturing, process control, and material handling. It is ideal for extending the I/O capacity of legacy S5-135U and S5-155U installations in industries such as power generation, chemical processing, and steel production.