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corE.rolled output to the 1403.
This makes
the three-phase ac power available for the
motors..
The +60 volts controlled must be
down to or below a sensed level before
removing other de voltages used by the
1403.
5.6
9
1.3 2311 DC Power
The first de power on the 2311 is the +6,
+ 3., and -3 volts; then the ac power-on
control line is activated.
'lbe first step
in power-off is to deactivate the •power-on
con:. rol' line, remove ac power, and finally
remove de voltages.
The 2311 heads
extended prohibit sequence down unti 1 the
heads retract or an EPO occurs.
5.6 .• L.4 2540 DC Power
The -20 volt de power to the 2540 is
applied at the same time as the -30 volts
is supplied to main storage.
5.6.1.5 2560 AC Power
The ac to the 2560 is applied after the de
voltages and removed before the de
voltages.
5. 6. 2 POWER ON/OFF TO CHANNEL CONTROLLED
I/O UNITS
A
maximum
of eight I/O control units can be
cont rolled
by
the CPU channels.
These
units are powered up after all CPU and
integrated I/O units have been sequenced
on.
The channel controlled I/O units step
their power on one at a time.
When the
last I/O unit has completed its power-on
sequence Wlder remote control and the
memoi:y temperature is alx>ve the low limit.,
the system power-on reset
lin~
is
deactivated and the system power-on light
is turned on.
Power off occurs in the same sequence as
power on, with the following exception:
if
the 2311 heads are extended at the time of
power off, the power-down sequence is
prchibited until the heads retract or an
EPO occurs.
5.7 EMERGENCY POWER-OFF (EPO)
Operation of the emergency-pull switch
removes primary power within two seconds
from the
CPU
and every I/O control unit
attached to a channel simultaneously, and
without stepping down.
An emergency
power-off can cause the data in main
storage to be lost.
Operation of the
emergency-pull switch sets a mechanical
latch within the switch mechanism that must
be manually reset before power can be
restored.
5. 8 OVERCURRENT,, UNDERVOLTAGE, AND
OVERVOLTAGE
SENSE
When an overcurrent or an overvoltage
condition occurs on de power supplies with
an overcurrent CB, the following events
take place.
1.
A circuit breaker is tripped and the CB
trip light is on.
2.
A normal power-off sequence is
initiated.
3.
A power-check light is energized on the
console.
The de power supplies not provided with
an overcurrent CB are fused for overcurrent
protection.
I.oss of the supply outputs
when system power is on initializes a
normal power-off sequence and turns on the
power-check light on the console panel.
Loss of the +24 volt supply causes a random
power off and does not light the power
check light.
Loss of any de supply <except the +24
volt) below its se.i.sed rating initiates a
normal power-off sequence and lights the
power-check light on the console panel.
The 20-volt, 24-volt, 36-volt, 48-volt,
and 60-volt de supplies do not require
overvoltage circuits.
5.8.1 SYSTEM-RESTART/POWER-CHECK LIGHT
RESET
system restart can not be accomplished
without first pressing the power-off bltton
to res
et
the power- check 1 ight.
Inability
to reset the power-check light indicates
the power failure is caused by an
overcurrent, overvol tage., or thermal-trip
condition.
The system power-off hltton
must be pressed after resetting the
condition at the power tower.
5. 9
THERMAL SENSING
Thermal sensing switches are provided on
logic gates, main storage, and power supply
areas.
Whenever any of these thermal
switches senses a temperature in excess of
their specified limit, the following
occurs .•
1.
A normal power-off sequence is
initiated.
2.
The thermal-trip
1
ight on the power
tower is turned on and remains on until
the condition is corrected and the
thermal reset switch is actuated.
3.
The power- check 1 ight on the console is
turned on.
2025 FEMM (7/69)
5-3
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