Users Manual Part 1

Figure 14: Opto-isolated Alarm Input Structure
Alarm
Indication
Schmitt
Trigger
Opto-Isolator
Contact Closure
(External to Alarm Card)
Vsupply
12VDC
RC Filter
Debounce / Noice Rejection
3.9
Grounding Requirements
WARNING: The MTS site must meet certain specifications for adequate protection from
lightning induced transients. Proper ground installation methods are outlined in the Motorola
Standards and Guidelines for Communications Sites, R56.
NOTICE: The methods and standards cited in the following paragraphs are typical. Local
codes, statutes, regulations, and standards supersede any information provided.
Use single-point ground method (where each cabinet is grounded to master ground using its own
ground wire). For equipment cabinet, use green (or green-yellow) insulated wire with a minimum size
of 16 mm
2
CSA (#5 AWG) for ground wire.
Ground any external -48 V DC power system in accordance with manufacturers instructions and any
applicable local regulations.
NOTICE:
The MTS cabinet is wired to positive earth but the Power Supply Unit inside has a floating DC
ground concept.
You can use different wire colors according to the local standards.
If the specified wire size is not available, use the next-larger available wire size.
During the installation of the cabinet ground wires, check any factory-installed internal ground
connections for tightness.
6802800U74-AP
Chapter 3: Site Preparation
88