TECO-Westinghouse PA7300 Series, Installation And Operation Manual

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• 4th digit (operation select upon loss of frequency reference)
4th digit = 0: Normal operation (varies with change of reference)
4th digit = 1: Operation continues at 80% of last known frequency.
When the 4th digit = 1, the current master speed frequency reference is continuously compared
with the reading that occurred 0.4 seconds prior. When the current master speed frequency
reference goes below 10% of the prior reading, operation continues at 80% of the last known
master speed frequency reference. Then the master speed frequency reference read becomes
the prior current frequency reference. In the following cases, this operation is released and the
AC drive returns to normal operation:
• Master speed frequency reference exceeding the 80% frequency is commanded.
• Stop command is asserted.
• The reference is missing during operation at less than 5% of maximum frequency.
(7) Operation Mode Select 4 (Sn-07)
Define the operation for overtorque detection. Overtorque is detected by the following formula:
AC drive output current overtorque detection level (Cn-26, Initial value: 160 %)
(Detection time Cn-27, Initial value: 0.1 second, Hysteresis fixed at 10%)
• 1st digit
1st digit = 0: Overtorque is not detected.
1st digit = 1: Overtorque is detected.
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PA 7300 PART II: OPERATION MANUAL
80%
10%
80%
FREQUENCY LEVEL
0.4
Sec
TIME CHART
AC DRIVE
OUTPUT
FREQUENCY
MASTER SPEED
FREQUENCY
REF.
FWD RUN
COMMAND
0.4
Sec