ABB IEMMU21 Bailey INFI 90 Module Mounting Unit

Configured for module mounting and backplane interconnection in ABB INFI 90 / Symphony / Harmony control systems, the ABB IEMMU21 (IEMMU21 Module Mounting Unit) provides the mechanical mounting structure and internal bus connections for system modules. This rear-mount unit accommodates up to 12 modules, or up to 10 modules when two power modules are installed, subject to system configuration.

Hardware Specifications

Backplane Bus and Power Distribution

The IEMMU21 provides the physical mounting and electrical interconnection structure for compatible INFI 90 family modules. Its backplane supports the module bus, I/O-expander bus, and Controlway signals while distributing regulated DC supply voltages to installed modules.

The module capacity depends on the installed power-module arrangement. A configuration with two power modules reduces the stated capacity from 12 modules to 10. Before installing replacement modules, verify chassis compatibility, slot allocation, power-module placement, and backplane connector condition against the applicable ABB system documentation.

The listed primary power specifications for the IEMMU11/IEMMU12 must not be interpreted as direct input-power ratings for the IEMMU21. Confirm the applicable power-entry and supply arrangement for the installed chassis.

Frequently Asked Questions

Q: How many modules can the IEMMU21 accommodate?

A: The stated capacity is up to 12 modules, reduced to 10 modules when two power modules are installed. Confirm the system configuration and slot allocation before installation.

Q: Which electrical connections does the mounting unit provide?

A: The chassis supports the module bus, I/O-expander bus, Controlway signals, and distribution of regulated DC voltages. The installed modules and power configuration determine the applicable electrical interfaces.

Q: What environmental conditions apply to the IEMMU21?

A: The supplied specifications state an internal cabinet operating range of 0 to 70 deg C, with humidity limits dependent on temperature. Storage is specified from -40 to 85 deg C, with noncondensing relative humidity up to 95%.

Field Installation Guidelines

1. Verify chassis compatibility. Confirm that the IEMMU21 is suitable for the installed ABB INFI 90 / Symphony / Harmony system and the intended module arrangement.
2. Inspect the cabinet mounting location. Check the rear-mount supports, cabinet alignment, fastening points, and available clearance before positioning the chassis.
3. Isolate power before installation. Follow the site lockout procedure and verify that the relevant power sources are de-energized before handling the chassis or its connections.
4. Inspect the backplane. Check connectors, contacts, mounting hardware, and the chassis structure for contamination, corrosion, or mechanical damage.
5. Install modules in approved positions. Follow the applicable system documentation for module placement, power-module allocation, and the maximum supported module count.
6. Check grounding and bonding. Follow ABB cabinet and system grounding instructions. Do not assume that signal common connections replace protective chassis bonding.
7. Maintain wiring separation. Route power and field wiring separately from sensitive signal wiring where required by the system design. Avoid obstructing cabinet ventilation paths.
8. Verify the assembled system. Before restoring power, confirm mechanical security, connector engagement, power-module placement, and wiring integrity. Check system status after startup according to the applicable commissioning procedure.