Service Manual

6802800U74-AN
Chapter 3: Site Preparation
85
• 2 x Form A relay outputs with Common and Normally Open contacts: Available on the junction
panel.
• DOOR alarm: Connected to the Site Controller
NOTICE:
All 15 alarm inputs and Door alarm use the same Alarm Ground. All these alarms and controls
connect directly to the Site Controller (SC).
The Expansion Cabinet only offers the Door alarm feature.
For detailed information, see External Alarm Cabling on page 138 and User Alarms/Controls,
X.21, RGPS, and GPS Cabling on page 155.
The following figure shows detailed User Alarms input structure.
Figure 13: Opto-isolated Alarm Input Structure
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.
Schmitt
Trigger
Vsupply
12VDC
Alarm
Indication
RC Filter
Opto-Isolator
Debounce / Noice Rejection
Contact Closure
(External to Alarm Card)