switchover to battery source is automatic for
The power supply (fig. 6-50) does two essential
uninterrupted service. Once normal power is restored,
jobs in the system. It provides +48 volt dc and talk
automatic switchback is again accomplished.
battery. Secondly, it provides the 90-volt ac 20-Hz
Monitoring battery charging rate and voltage level,
ringing current for line station ringing. Included
including battery maintenance, is essential in
within the power supply is a battery charging network
maintaining the Dynalec 200/500 central office
with all controls and indicators mounted on the door
system free of power-related faults.
(fig. 6-50). Should a loss of ac power occur,
Figure 6-50.--Terminal power supply.