Specifications

Alto 818 Installation and Operation
4-2 P/N 66109074001 Rev. D
4.1 AC POWER
The SE 3708CU or the SE 3718SU power module is connected to both the primary AC line power
and to the ACU. If required, the SE 3708CU or the SE 3718SU can be connected to backup
battery power.
Both the SE 3708CU and the SE 3718SU power modules require a 115 VAC (+ 10%), three-wire
(single-phase) primary power circuit with a low resistance ground (green) conductor. This input
power line must have a dedicated circuit breaker providing AC power to the power module and
any modems in the system. WSE recommends that a constant voltage transformer with a spike
filter be placed in this line.
The primary power cable may be either exposed cable or in conduit. Its gauge and wire type must
meet the requirements of the National Electrical Code and it must have low resistance through
its earth-ground connection.
Use of an AC line with more than one AC circuit can result in electrical noise from other devices
such as motors, etc. Use of a non-dedicated AC circuit can cause unacceptable variations in
power to the power modules. The ideal power source is a dedicated uninterruptible power supply
for the Alto 818 system.
When the Alto 818 and a terminal/printer are connected via null modem cables, they must use
the same AC line and/or the ground points must be at the same physical connection point.
4.1.1 GROUNDING
The building codes in many cities allow two-wire AC with conduit for ground. WSE recommends
that the electrical contractor should be directed to run two conductors with a separate ground
wire.
4.1.2 ACU CONNECTION
The SE 3708CU and SE 3718SU power modules are connected to the ACU by a 6' 5" shielded,
9-conductor cable supplied with the power modules. The cable plugs into the power connector
on the Alto 818 . Refer to Figure 4-1 for wiring diagrams of these connections.