Allen-Bradley PowerFlex 70 Reference Manual

2-60 DC Bus Voltage / Memory
DC Bus Voltage /
Memory
[DC Bus Voltage] is a measurement of the instantaneous value. [DC Bus
Memory] is a heavily filtered value or “nominal” bus voltage. Just after the
pre-charge relay is closed during initial power-up bus pre-charge, bus
memory is set equal to bus voltage. Thereafter it is updated by ramping at a
very slow rate toward Vbus. The filtered value ramps at approximately 2.4V
DC per minute (for a 480V AC drive).
Bus memory is used as the base line to sense a power loss condition. If the
drive enters a power loss state, the bus memory will also be used for
recovery (i.e. pre-charge control or inertia ride through upon return of the
power source) upon return of the power source. Update of the bus memory
is blocked during deceleration to prevent a false high value caused by a
regenerative condition.
Decel Time [Decel Time 1, 2]
Sets the rate at which the drive ramps down its output frequency after a Stop
command or during a decrease in command frequency (speed change). The
rate established is the result of the programmed Decel Time and the
Minimum and Maximum Frequency, as follows:
Two decel times exist to allow the user to change rates “on the fly” via PLC
command or digital input. The selection is made by programming [Decel
Time 1] & [Decel Time 2] and then using one of the digital inputs ([Digital
Inx Sel]) programmed as “Decel 2” (see Table 2.I
for further information).
However, if a PLC is used, manipulate the bits of the command word as
shown below.
The effectiveness of these bits or digital inputs can be affected by [Decel
Mask]. See Masks
on page 2-114 for more information.
Times are adjustable in 0.1 second increments from 0.0 seconds to 3600.0
seconds.
In its factory default condition, when no decel select inputs are closed and
no time bits are “1,” the default deceleration time is [Decel Time 1] and the
rate is determined as above.
Maximum Speed
Decel Time
= Decel Rate (Hz/sec)
011000010111
1
0
0
0
Accel 1
Accel 2
Decel 1
Decel 2
0
1
0
0
0
0
1
0
0
0
0
1
0000
10 01234567891112131415
1 = Condition True
0 = Condition False
x = Reserved
Bit #
Stop
Start
Jog
Clear Fault
Forward
Reverse
Local Contrl
Mop Inc
Accel 1
Accel 2
Decel 1
Decel 2
Spd Ref ID 0
(1)
Spd Ref ID 1
(1)
Spd Ref ID 2
(1)
MOP Dec

Allen-Bradley PowerFlex 70 Specifications

General

Brand	Allen-Bradley
Model	PowerFlex 70
Category	Controller
Language	English