Figure 6-50.--Terminal power supply.

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.

6-62