Appendix F
125
The time constant is NOT the time until foldback occurs. It is a parameter based upon the
motor's physical characteristics.
Three variables (continuous current, actual current, and time constant) affect the amount of
time that the foldback circuit allows operations to continue before foldback occurs. For a full
explanation of the foldback circuit, see Chapter ƒ Advanced Features. The following equation
gives an approximate time, in minutes, for a motor that operates from a cold start.
time
(in minutes)
= Time Constant − ln 1−
I
continuous
I
actual
2
I
continuous
is the continuous current, which you selected when you set switches #1, #2, and
#3. I
actual
is the actual peak current, whose maximum value you selected when you set
switches #4, #5, and #6.
Switch 3 (SW 3)
RESERVED — #1: Set this switch in the OFF position.
ALIGNMENT MODE — #2: Turn this switch OFF. If you need to align the resolver,
you will turn this switch ON during the alignment procedure, and turn it OFF when you have
finished aligning the resolver. This switch must be OFF during normal operating conditions.
See Chapter ƒ Advanced Features for more information.
COMMUTATION TEST MODE — #3: Turn this switch OFF. If you need to operate
the drive in commutation test mode during a troubleshooting procedure, you will turn this
switch ON during the procedure, and turn it OFF when you are finished. This switch must be
OFF during normal operating conditions. See Chapter
∆
Troubleshooting for more
information.
HALL SELECT — #4: Turn this switch OFF if your motor has a resolver. (This switch
should be OFF if you use an APEX motor, all of which have resolvers.) Turn this switch ON
if your motor has Hall effect sensors instead of a resolver.
TACHOMETER SCALING — #5: This switch scales the tachometer output. If you use
a motor that has a single speed resolver, turn this switch OFF to scale the tachometer output
to equal 1 volt per 1,000 rpm. (This
switch should be OFF if you use an APEX motor, all of which have single-speed resolvers.) If
you use a motor that has a two-speed resolver, turn this switch ON. This will adjust gains of
the internal circuitry, so that the tachometer output is scaled to equal 1 volt per 1,000 rpm for
two speed resolvers.
RESERVED — #6, #7, #8: Set these three switches in the OFF position.
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