Application Note

Grounding Your ASTi Peripheral Devices (#111)

ASTi doesn’t require customers to ground peripheral devices like ACE-RIUs, ACU2s, and AI-Deltas, but we designed them to accommodate facilities with stringent grounding policies. Most of our customers don’t ground these devices and have no problems.

If you need to ground your device, follow these tips:

1. Attach the grounding wire: use a #10 grounding ring connector to attach the grounding wire to the device chassis at the stud. This step is necessary due to the stud’s size and not necessarily the wire gauge.
2. Choose the right wire: connect the grounding ring connector to at least 18 gauge (AWG) stranded, braided, or strap wire. For best results, avoid using solid wire, as it’s difficult to work with and may break.
3. Minimize wire length: keep your grounding wire as short as possible to reduce resistance and dissipate any unwanted electrical charge.

Ground Loops

ASTi recommends installing peripheral devices isolated from Earth ground to eliminate ground loops, especially for Voisus Radio Bridge applications. Ground loops can introduce noise into the system if an ACE-RIU and a radio connect to grounds at different locations and "Earth" potentials.

Here are some tips to improve system performance:

• Only connect the ACE-RIU to the ASTi-provided isolated power supply.
• Do not bond the ACE-RIU chassis to Earth ground through any contact. This can be challenging when rack-mounting an ASTi peripheral device, as it often requires Earth-grounding the rack structure.
• Avoid connecting ACE-RIU ground (i.e., Pin 5 on the A-D Channel connectors) to Earth ground. This guidance also applies to the ACU2; however, our experience shows that the ACE-RIU is more susceptible to ground loops.

Note: Make sure to shield audio and input/output (I/O) cables and carry an Earth ground from the source device to the sink device. ASTi highly recommends Earth-grounding at a single "star Earth point" (i.e., the location where all grounds converge).