Troubleshooting Guides - Rotary Converters, Static Converter, Power Factor Capacitors

Posted on October 19th, 2016 by vapro

Rotary Converters


A rotary converter is a device that uses an electric motor and a bank of capacitors to generate and maintain a third leg of power from a single-phase source. There are three things that have to be adequate for the generated leg to be of use. 1) The incoming power must be adequate in the aspect of voltage. This is achieved through the wire and other devices that bring the power to the converter. A phase converter can be a part of a successful electrical system for years, and then, all of the sudden, it can appear to quit working. Many times this can be attributed to a change in the supplied power. Once it is determined that the converter is getting adequate power, the two other items can be addressed. 2) The capacitors in the converter boost the voltage of the generated leg and help the generator motor to start. If the capacitors are bad, there aren’t enough of them, or they are misconnected, the converter and load motor may not come up to speed. 3) Lastly, the generator motor can be damaged by lightning or some other means and not be able to provide the power required.

Trouble: Rotary or Load Motor fails to come up to speed

  1. Check main fuses. Fuses should be dual element type
  2. Check voltage coming from the phase converter during starting of load motor. Voltage should not dip below 210 volts for the 230volt model and not below 420 volts for the 460volt model. If the voltage dips below these values, check wire size and transformer KVA. Refer to the Wire & Device Sizes page for proper sizing.
  3. Check for proper wiring, Refer to Wiring Diagrams page. Single Phase L1 & L2 must be connected to the Rotary L1 & L2.
  4. Check inside rotary panel for signs of defective capacitors. If a capacitor has a bulged case, it is defective and should be replaced. To further check a capacitor see How to Test a Capacitor Cell.
  5. Check the starting code letter of the load motor. If the motor has a high starting code letter or is under a high inertia load (large flywheel type), an auxiliary start panel may be required. Consult the factory.

Trouble: Rotary vibrates or is excessively noisy

  1. Make sure that converter is securely bolted to the floor or surface it is resting on. A rubber mat or similar device may be placed under the converter before bolting it in place.
  2. Some noise and vibration is normal, especially under no load conditions. As the rotary is loaded, it will run more quietly.

Trouble: Load motor overheats or generated voltage is too high when load motor is running

  1. If current is excessive in the G# generated phase, and voltage across L2 & G3 is high, disconnecting one or more capacitors may balance the generated voltage better.

Static Converter

Key things to remember when troubleshooting an HAS Static Converter:

  1. The HAS Static Converter must be mated to a 12 lead motor. The motor must also be wye-wound for 230-volt applications.
  2. Verify that the motor leads are tied together properly and mated to the correct corresponding converter terminal. For details, see the HAS Static Converter Installation Instructions, page 3 or 5.
  3. The HAS Static Converter may only run the horsepower motor that is indicated on the nameplate.
  4. Foreign made motors are not recommended for use with the HAS Static Converter.

Trouble: Motor does not start (does not hum)

  1. Check all motor controls for proper wiring. Make sure magnetic starter coil is energized by voltage between L1 & L2 or by control power from a separate source. Do not have one side of coil wired to T3.
  2. Check all fuses and heaters for proper sizing as shown on Page 5. Replace if necessary.
  3. Check all connections from converter terminals to motor. Connections should be as shown on Pages 3 or 5 of the Installation Instructions.
  4. Check voltage between terminals T1 & T2. Voltage should be 220 – 250 Volts for the 230 Volt model and should be 430 – 480 Volts for the 460 Volt model.

Trouble: Motor does not start (but does hum or rotate slowly)

  1. Check for incorrect or crossed wires between motor and converter.
  2. VERY IMPORTANT! Using an accurate voltmeter, check voltage between T1 & T2 on the HAS while motor is trying to start! If the voltage drops below 210 volts for the 230-volt model or below 420 volts for the 460-volt model, the service wire or the transformer is too small. The transformer should be at least 1 KVA per horsepower. The table on Page 5 of the Installation Instructions lists wire sizes for installations that do not exceed 50 feet.
  3. Check all parts per procedure shown below.

Trouble: Motor starts but slows down after full speed has been reached or re-enters the starting cycle.

  1. Check voltage from T1 & T2. Voltage must be at least 210 volts for 230 volt HAS and 420 volts for the 460-volt HAS.
  2. Check run capacitors and replace of defective.
  3. Motor may be overloaded if this problem is not encountered under "no load" conditions. (see Installation Checkout Instructions on Page 10 of the Installation Instructions). Check full load amps T1 prior to re-entering the starting cycle, and if amperage exceeds value calculated from Explanation of Operation on Page 6 of the Installation Instructions, the motor is overloaded. Reduce load or replace motor and converter with a larger HJP size. Remember, the converter must be the same HP size as the motor.

Trouble: Motor starts and runs properly except heaters trip overload relay.

  1. Check for undersized heater coils. See Explanation of Operation on Page 6 in the Installation Instructions for calculation of heater coil sizes.
  2. Check for overload. If L1 amperage calculated in 1 above is exceeded when measured with an ammeter, the motor is overloaded.
  3. Check for excessive amperage for T3 with an ammeter. If amperage calculated in 1 above is exceeded under normal load conditions, the converter requires adjustment of its run capacitance. Consult factory.

Trouble: Relay Chatters

  1. Adjust the Relay Control according to Installation Instructions, Page 3.
  2. Check voltage from T1 to T3. Compare reading to values shown on Installation Checkout Instructions on Page 10. If value does not fall within the range given, complete the troubleshooting data sheet and consult factory.

Trouble: Motor heats abnormally

  1. Check for overload. (See table on Page 4 of the Installation Instructions for appropriate amperages.)
  2. Check for low voltage.
  3. Check for improper or loose connections.
  4. If problem is not solved by above, complete troubleshooting data sheet and consult the factory.

Trouble: Run capacitors repeatedly become defective.

  1. Complete troubleshooting data sheet and consult the factory.

Trouble: Electrolytic capacitors repeatedly become defective.

  1. Check duration of starting cycle. It should not exceed 15 seconds.
  2. Check motor for severe overload (the motor may re-enter the starting cycle repeatedly).
  3. Check for burned discharge resistors. Resistors should read approximately 10,000 ohms each.
  4. If a problem is not solved, complete troubleshooting data sheet and consult factory.

Procedures for checking parts

Electrolytic Capacitors

  1. Remove capacitors completely from circuit and check for sorts (use ohmmeter only).
  2. Look for traces of oil oozing from capacitors. This indicates capacitor has been overheated and capacitor may be defective. Check for short circuits.

Run Capacitors

  1. If capacitor is swollen or disfigured, it is definitely bad and should be replaced.
  2. Check amperage in leads going to capacitor when in operation. If capacitor is open, no amperage will flow.
  3. Remove from circuit and check for short circuits or grounds (use ohmmeter only).

Variable Resistor

  1. Using ohmmeter, check control for continuity, opens, or grounds.
  2. A good resistor should read approximately 2500 Ohms across its two outside terminals.

Relay, Normally Closed

  1. Check coil with an ohmmeter for opens or grounds.
  2. Check armature for sticking or for faulty contacts.

Contactor, Normally Open

  1. Check same as for normally closed relay.
  2. If contactor is checked by energizing coil, remember that contactor must be in a vertical or upright position for proper operation.

Fixed Power Factor Correction Capacitors

Trouble: Pilot light is illuminated.

  1. This indicates that a fuse is blown. Typically, power surges or a bad capacitor causes a fuse to blow.
  2. Disconnect power from the capacitor unit and wait one minute after the power has been disconnected to allow the capacitors to discharge.
  3. Check affected capacitor following steps found in How to Test a Capacitor Cell.
  4. Replace affected capacitor, if it is bad, and fuse.

Trouble: It appears that the unit is not providing the full KVAR rating.

  1. Check amperage draw of capacitor unit while it is connected to power. For 480-volt units, the amperage should be 1.2 times the KVAR rating. For 240-volt units, the amperage should be 2.4 times the KVAR rating. If the amperage is low, complete the next three steps.
  2. Disconnect power from the capacitor unit and wait one minute after the power has been disconnected to allow the capacitors to discharge.
  3. If the unit has fuses, check the fuses using an ohmmeter. Replace any blown fuses.
  4. Check the capacitors following steps found in How to Test a Capacitor Cell. Replace bad capacitors.

Automatic Power Factor Correction Capacitors

See Var Manager Installation Instructions or consult the factory.

Capacitor Converters

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