Motor Starting Adjustments; Potentiometer Settings - Siemens Sikostart 3RW34 Instruction Manual

4. Measure individual input AC voltages L1, L2 and L3 to
ground. On most systems, voltage will be about 57% of line
voltage and nearly equal. Any unbalanced voltage may indi-
cate an undesired ground in the motor or the SIKOSTART
controller.
5. Measure the control voltage. It should be within -15% to
+10% of the nominal controller rating.6. Measure voltage
across each pole of the SIKOSTART controller, i.e., L1 to T1,
L2 to T2, and L3 to T3.
These voltages should be nearly equal and have values as
follows:
a. For a wye motor, voltage across each pole should be
approximately 57% of input line to line voltage.
b. For a delta motor, voltage across each pole should be
approximately 100% of input line to line voltage.
Low voltage, zero voltage, or unequal voltages indicate 1)
the load circuit to the motor is open or improperly grounded,
or 2) an SCR is shorted or bad (usually indicated by a double
flashing LED 2; refer to the troubleshooting section).
To check the load circuit, disconnect power to the controller,
check and correct connections and close any load circuit
switching device(s). Energize the controller and recheck
voltage across each pole.
7 . De-energize main AC power and control power. Unit is now
ready. Reconnect actuating signal wires to terminals A1 and
A2.
8. Energize main AC power and control power. Initiate start by
actuating pilot device(s). Check for proper operation and
desired starting performance. Verify proper motor rotation;
if required, reverse rotation by interchanging motor leads.
Adjust potentiometers per paragraph 6.6.
Initial Voltage _______________
(0 is minimum, F is maximum)
30
Figure 21 - Potentiometer Settings
Start Time ________________
(0 is minimum, F is maximum)
Record the final potentiometer settings in the blank spaces above.

6.6 Motor Starting Adjustments

Hazardous voltage.
Can cause death, serious injury or
property damage.
To avoid electrical shock or burn, turn off
main and control voltages between
starts when making adjustments.
Observe the motor during the first trial starts. With the setup
controls adjusted as described in paragraph 6.3 and controller
LED 1 on, start the motor.
Initial Voltage U. Ideally, the motor begins to rotate almost
immediately after starting voltage is applied to it and the load
begins to move. If the motor fails to start rotating when the
starting voltage is applied, increase the U potentiometer setting.
If the motor accelerates too quickly, decrease the U setting.
Repeat trial starts until the load just begins to move when
power is first applied.
Additional initial voltage may be needed if motor is subject to
starting load variance such as stiff belts, cold grease or process
loading.
Start Time T1. During setup procedures, T1 was set to a mid
range acceleration ramp time.
before the motor reaches full speed, turn run signal off and
increase the T1 setting. Repeat trial starts to achieve a smooth
acceleration to full speed (LED 2 changes from single blinking
mode to continuously on) before the T1 time elapses.
Stop Time T2. For most applications, the motor load will coast
to rest; T2 setting equals 0.
A soft stop is required for some applications, e.g. to reduce
water hammer in a pumping system. For a soft stop, most appli-
cations require the stop time T2 to be equal to or longer than the
start time T1. Turn run signal off before changing the T2 setting.
Stop Time _________________
(0 is minimum, F is maximum)
Siemens Energy & Automation, Inc.
If the controller ramp ends