Ring Communications CB901EX - Manual (Page 15)

April 2012 Operations Manual CB901EX
C. Location of existing telephone ducts or conduit.
D. The AC line should be dedicated exclusively to the system. If the line is equipped
with a circuit breaker at the service entrance panel, the circuit breaker switch should be labeled
«DO NOT TURN OFF».
E. The equipment should be installed in an area that has adequate ventilation. A
temperature range of 0 o C (32 o F) to 25 o C (77 o F) and humidity range of 30% to 90%
relative must be maintained.
F. Appropriate lighting conditions and adequate working space should be provided for
future service calls.
G. Consideration must be given to those conditions that may cause damage to the
equipment. For example, dust or vapor from flammable or corrosive solvent may
cause damage. The installation site should not be located in an area likely to be flooded
or likely to be damaged by moving objects nearby.
H. The central should NOT be installed in an area near electrical noise including
equipment, i.e., heavy motors, welders, dimmers, radio transmitters etc.
I. The power supply (or transformer) must not be mounted below the central. This is to
prevent overheating the central.
CABLE REQUIREMENTS
Each station is connected to the central by 4 leads (in two twisted pairs).
Leads No. 1 and No. 2. Audio and signaling.
Individual leads i.e., a separate twisted pair is required for each station. This pair carries
tone-signaling (CCITT norm.) for dialing, audio transmission and DC control signals for stations.
The maximum loop-resistance of this pair is 240 ohm corresponding to approx. 2km cable-length
from station to central, using normal telephone cabling with 0.6 mm diam. wiring. If the actual distance
is more than 2 km. (loop resistance more than 240 ohm) doubling this audio pair (or using heavier
cable) can cause incorrect dialing transmission, since the capacitance in the cable is also increased.
Doubling is not recommended. If cable to a station passes close to radio aerials or other interference
sources, the leads to the actual station should be shielded.
Leads No. 3 and No. 4. Station Operating Voltage.
These leads carry operating voltage to the stations. The maximum/ minimum station voltage for
proper operation is 21 - 28.5 V. This allows a loop resistance between each station and power supply
(centralized or local) of 40 ohm, giving a distance of 350 meters on 0.6 mm copper wire and 600 m on
0.8 mm. (based on power supply output of 27V DC).
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