Getting Acquainted With Electronic Igniters

You may have noticed in the last ten years an increase in the number of appliances that use electronic or “solid state” ignitors. To help you become more familiar with this device and its operation, we have compiled a list of some features and characteristics of electronic ignitors, as well as tips for servicing and troubleshooting them.

FEATURES OF ELECTRONIC IGNITORS

Electronic ignitors:

• mount on a burner housing baseplate similar to that of a transformer.
• are smaller (1/4 to 1/2 the size) and weigh less than a transformer (1lb. compared to 8lb.).
• have oil ignition characteristics similar to that of a transformer.
• offer improved performance with cold oil or delayed spark conditions.
• have output currents and peak voltages that can be up to double that of iron core transformers.
• produce a spark intensity that can be less sensitive to line voltage fluctuations.
• are epoxy sealed for moisture resistance and have oil-resistant, non-rusting plastic enclosures, epoxy will not shrink and crack like a tar filled transformer, leading to premature failure.
• consume 50 to 75% less power than transformers.

USEFUL TERMS AND DEFINITIONS

CONSTANT DUTY means that the ignitor is designed to be able to stay on continuously. Constant duty ignitors therefore can be used with controls that operate the ignitor with either intermittent or interrupted duty ignition. Most ignitors, unless labeled otherwise, are rated for constant duty.

INTERMITTENT DUTY IGNITION is defined by Underwriters Laboratory (UL) as “ignition by an energy source that is continuously maintained throughout the time the burner is firing.” (UL 296, Paragraph 4.22). In other words, the ignitor is on the whole time the burner is firing.

INTERRUPTED DUTY IGNITION is defined by Underwriters Laboratory (UL) as “an ignition system that is energized each time the main burner is to be fired and de-energized at the end of a timed trial for ignition period or after the main flame is proven to be established.” (UL 296, Paragraph 4.21). In other words, the ignitor comes on to light the flame, and then after the flame is established, the ignitor is turned off and the flame keeps burning.

PEAK VOLTAGE is the maximum voltage reached as a voltage signal alternates positive and negative polarity (see Figures 2 and 3 below).

RMS (“Root-Mean-Squared”) is a time-weighted average of the voltage or current signal. If a current or voltage is sinusoidal, it has a peak value equal to 1.4 times the RMS value.
SINUSOIDAL voltages alternate positive and negative polarity very smoothly and in a continuous “S” shape (see Figure 2 below).

SOLID STATE means that the electronic unit includes semiconductor components, such as diodes, LED’s, triacs, microprocessors, and other transistors.

HERTZ (abbreviated Hz) is a unit of frequency. Line voltage alternates at 60 Hz, or 60 cycles per second.

HOW AN ELECTRONIC IGNITOR WORKS

IRON CORE TRANSFORMERS draw 120 VAC (Volts, Alternating Current) into their primary coil. The steel plates of the transformer core transfer the primary coil’s 60 Hz magnetic field to the secondary coil. The secondary coil uses this field to produce a high output voltage of 10,000 VRMS open circuit (when there is no secondary current flowing) that has a frequency of 60 Hz.

ELECTRONIC IGNITORS receive 120 VAC and change it to DC (Direct Current) voltage inside. The DC voltage turns power transistors on and off very quickly, conducting current through the primary coil of its small internal transformer at a frequency of 15,000 to 30,000 Hz. The secondary coil of this special high frequency transformer produces a high voltage ignitor output that has a frequency of 15,000 to 30,000 Hz. Remember: the ability of an
ignitor to ignite oil depends on more than just high voltage – it depends on arc output current as well! Spark heat energy = voltage x current.

SERVICING IGNITORS

The electronic ignitor does not require extensive maintenance. However, there are areas to consider:

1. Similar to the iron core transformer, the electronic ignitor must be kept clean. Prolonged exposure to moisture can cause arc tracking and potential failure to ignite. Wipe dirt and oil from all surfaces.
2. Check insulator bushings and make sure they are clean and free from any crazing or cracks. Replace units that show evidence of damage.
3. Examine the ignitor input leads for cuts or tears in the insulation. Route the leads securely so that they are not pinched when the ignitor is closed. Make sure the wire nuts are tight and no bare wires are exposed.
4. If the ignitor has gasketing, check the sealing surfaces and replace any damaged or deteriorated gaskets. (Use gasket kit No. 51304 for AFG and ADC burners.)
5. The secondary electrode springs should be clean, should be aligned perpendicular to the ignitor base, and should make solid contact with the burner electrode rods when the ignitor is in the closed position. If the springs make poor contact, the ignition performance could be impaired (see Figure 4 insert).
6. Perform the following test to check that the ignitor is grounded to the burner. Turn off the power to the burner.
   The Ohmmeter resistance between an electrode spring and the exposed metal of the burner (for instance, the copper line or a housing bolt) should be less than 2000 Ohms. If this resistance is infinite, the ignitor is not grounded to the burner. Note: This resistance should be the same as the other spring-to-burner resistance, and it should be 1/2 of the spring-to-spring resistance. If the two spring-to-burner resistances differ by more than 20%, the ignitor should be replaced.

TROUBLESHOOTING ELECTRONIC IGNITORS

HOW TO TEST ELECTRONIC IGNITORS

WARNING SHOCK HAZARD: Though this test is common industry practice, be careful not to physically touch any part of your body to the ignitor springs or anything metal that is touching the ignitor springs while the ignitor is energized.

CAUTION Just like an iron core transformer, an electronic ignitor is most simply tested by supplying it with 120 V input and observing whether it produces an arc. This may be done by looking or listening to see if there is an arc across the electrodes while the burner is running and the ignitor is energized. The ignitor may be tilted back on its hinge and, when voltage is applied, the blade of an insulated screwdriver may be placed across the springs to test for an arc.

Remove power from the burner and block the fuel supply to the nozzle line while performing this test.

NOTE: If the machine is equipped with a primary safety control the cad cell will not permit the primary control to energize the ignitor if the cad cell senses light. To perform this test, disconnect one lead of the cad cell from the primary control, or remove the cell from its base. DO NOT use transformer testers to test electronic ignitors. Doing so will give you an inaccurate measurement and may harm the ignitor, the tester, or both.

If an ignitor fails, it generally produces no arc at all. However, similar to an iron core transformer, an electronic ignitor can have a weak output arc. To test for this, perform the screwdriver arc test described above. Energize the ignitor and place the blade of the insulated screwdriver across the springs. Keeping the blade in contact with one of the
springs, slowly pull the blade away from the other spring, drawing an arc from the spring to the blade. With a 110 V to 120 V input and no airflow across the arc, the ignitor should be able to maintain an arc with the screwdriver blade at least 5/8″ away from the spring. If the ignitor is not able to sustain a 5/8″ spring-to-spring arc, or if an arc drawn from
one spring to the grounded baseplate is weaker than an arc drawn from the other spring to the baseplate, replace the ignitor. See also point 6 above.

TV INTERFERENCE

Electronic ignitors can produce interference with televisions and radios in two ways. First, if the ignitor is not designed with proper filtering or if it is not well grounded to the appliance and to the building, voltage signals can leak back through the power leads. The power lines radiate this “electronic noise” through the house, interfering with TV or radio
antenna signals. Secondly, if the electrodes are not properly adjusted, the strong arc produced by ignitors may jump over to the nozzle or combustion head. This may also produce electronic noise that can be detected by TV or radio antennas.

Iron core transformers can produce interference in the same ways, but usually to a lesser extent. Interference is most likely to occur in locations with old ungrounded “knob and tube” style wiring. Be sure the burner is properly grounded (see above, Service Tip #6), and check that the electrodes are correctly adjusted (see the appropriate Beckett burner manual for electrode settings).

MOISTURE AND AMBIENT TEMPERATURE

Ignitors utilize potting compounds and plastic materials that resist moisture well. However, excessive temperature is one of the primary causes of premature ignitor failures. Beckett ignitors are designed for a maximum ambient temperature of 150°F. If the pressure washer is installed in a van or enclosed trailer make certain that your customer
keeps the doors open. This is particularly important in the summer and the Southwestern part of the country where ambient temperatures routinely exceed 100°F.

IN CONCLUSION

Electronic ignitors have proven to be durable, effective ignition components. They have achieved wide acceptance in the pressure washer industry. Hopefully, this bulletin has further acquainted you with important features, performance, and service aspects.