Specifications

655A power supply
Issue 6 February 2007 215
● +8- to +14 VDC at 1.6 A (fan-speed control)
This output (+12 VDC nominal) controls the fans’ speed. The voltage varies with the
ambient air temperature at the inlet below the power supply. If this voltage reaches +14
VDC, the system activates a FANALM signal.
● –115 to –150 VDC at 200 mA (neon bus)
The 650A power unit has three switch-selectable outputs for ringing:
● 20-Hz AC output at 85 V RMS and 80 mA, — centered about –48 VDC at 180 mA
● 25-Hz AC output at 72 V RMS and 8 to 80 mA, — centered about –48 VDC at 180 mA
● Two 50-Hz AC outputs at 28 V RMS, effectively 56 V, and 220 mA, — biased about –48
and 0 VDC at 70 mA balanced
655A power supply
The G650 can use one or two 655A power supplies that can have both AC and DC input power
present. Either power supply can provide all the power needed by the G650. When there are
two power supplies, they share the power load. One power supply can operate on AC power
and the other on DC power. But, if AC power is available, the system always uses AC power.
The 655A power supply is:
● The only power supply supported in the G650
● Not backward compatible to other carrier types
If you use only one 655A power supply, place it in slot 0. If you are using two power supplies,
place them in slots 0 and 15.
Note:
Note: You can insert or remove a redundant power supply and not affect the G650 if the
other 655A power supply is operating.
Detailed description
Input power
The 655A power supply can operate on either AC or DC input power. But, if AC power is
available, the system always uses AC power. One power supply can operate on AC power, and
the other on DC power. The power supplies use AC power first and switch to DC power if AC
power fails or is not present.