Siemens Energy & Automation, Inc.
37
Table 8 Troubleshooting - Continued
Trouble Cause Check/Remedy
Motor growls at start Motor unable to start load Check load for mechanical blockage (rocks, logs, seized bearings,
and does not come etc.) Increase motor size; for proper controller selection, refer to
up to speed section 3.
Controller not finished Check that LED 2 is on, which indicates output voltage equals
ramping to line voltage line voltage. If motor is coming up to speed too slowly, decrease
Start Time T1 and/or increase Initial Voltage U; refer to
paragraph 6.6.
Shorted SCR (LED 2
double flashing) Check SCR’s as described in paragraph 9.4.
Motor comes up to Improper settings Adjust Start Time T1 and Initial Voltage U settings per
speed too quickly or too paragraph 6.6.
slowly
Load is too light Adjust load or consider decreasing or increasing motor size; for
or too heavy proper controller selection, refer to section 3.
Motor runs noisily with
very high current Inside Delta wiring problem See problem 1 in table 9.
Motor starts hard, Improper setup Refer to paragraph 6.6 for motor starting adjustments.
not softly.
Shorted SCR (LED 2
double flashing) Check SCR’s as described in paragraph 9.3.
Inside Delta wiring problem See problem 4 in table 9.
Unsuitable delta motor A certain delta motor design (wired Inside Delta) will not start
softly with a high friction load (e.g., conveyor), only with a low
friction load (e.g., water pump). The soft start produces balanced
three-phase power to the motor, but it becomes stuck at a low
rpm until the end of the start ramp at high current. It then jumps
quickly to full speed due to the high voltage and current. Consult
the factory for assistance.
Controller is off but Shorted SCR’s Check voltage from terminal A1 to A2 to verify that Run coil is
motor is running (LED 2 double flashing) not energized. Check SCR’s as described in paragraph 9.4.
Motor overload relay Motor is overloaded
trips during starting while running Check for a mechanical cause of overload and clear.
Motor not able to Check that motor comes up to speed when started by applying
accelerate load across-the-line full voltage directly to the motor. An alternative is
to use the controller with T1 set at 0 (0.5 seconds) and U at F
(80% full voltage).
a. If motor can’t accelerate the load, increase motor size; for
proper controller selection, refer to section 3.
b. If motor accelerates the load, continue checking the following
causes.
Improper overload
relay heaters Check heater table to determine correct heater size.
Overload relay current
transformers incorrectly
wired Verify current transformer wiring per applicable diagram(s).
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