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How to Intelligently Use an Arc Suppressor: Save Time and Equipment on the Production Floor
Thermex-Thermatron Systems

For over 80 years, Thermex-Thermatron Systems (“Thermex”) has served the industrial RF and MW industries, applying decades of technical expertise to trusted products. Leveraging Thermex’s range of dielectric heating systems, manufacturers can produce highly engineered, specialized components — improving quality, productivity, and safety around the world. 

When using high frequency dielectric heat sealers, it’s critical to have the right equipment to confront production challenges, so you don’t risk the price of overheating. Arcing leads to a breakdown in dielectric materials, leaving your equipment as well as your materials exposed. Thermex-Thermatron created the Arc Suppressor as an electronic protective device. Intelligent use of this Arc Suppressor will help you avoid costly damage to your equipment while saving you valuable time.

The Technology to Act Immediately to Curb Electrical Instability

Intended for use with Thermex-Thermatron high frequency dielectric heat sealers, the Arc Suppressor is an integral part of the generator, mounted inside the cabinet. During normal operation, the material being heated becomes more and more electrically conductive, until a point is reached when an arc can occur. Thermex’s Arc Suppressor has the capability to sense when the conductivity either has reached or is set to hit this arcing point. 

The technology acts promptly, stopping the high frequency power very quickly, usually before an arc is able to occur. In fact, power for the operation of the Arc Suppressor derives from the generator (to which the Arc Suppressor is connected). Even on the occasions when an arc does occur, the generator is quenched very rapidly, minimizing damage. 

Thermex Thermatron How To Intelligently Use An Arc Suppressor Stages of Arcing

Understanding How the Arc Suppressor Safeguards Your Equipment

The Arc Suppressor applies about 125 Volts DC across the work electrodes. Virtually no DC flows through when the electrodes are closed on the material being sealed. As the material becomes heated, its ability to conduct rises. 

When this current reaches or exceeds a definite level, it’s possible to adjust the sensitivity of the Arc Suppressor accordingly, so as to shut off the sealing power. If that level is properly set, the power will shut off at the completion of a normal seal. The continued heating of the material beyond the point at which a seal takes place could cause an arc to occur. This is when the Arc Suppressor preventatively acts. Sometimes, the time it takes for a normal seal to complete can trigger a current flow in excess of the adjusted level. Before this accidental occurrence of an arc can take place, the sealing power is rapidly removed with negligible die damage. 

Important Factors to Consider When Adjusting an Arc Suppressor

It is certainly true that the properly adjusted Arc Suppressor is capable of sensing the completion of a seal. However, it is not intended that the Arc Suppressor be used for this purpose. Keep in mind, the Arc Suppressor is intended to perform only a protective function.  

The adjustment of the Arc Suppressor depends upon several factors, including: 

  1. The thickness of the material being sealed. 
  2. The area of the die. 
  3. The quality of the material being sealed.
  4. The nature of the seal.
  5. The nature as well as the thickness of buffer material, if any used.
Thermex Thermatron How To Intelligently Use An Arc Suppressor Five Factors

The Model AS-5 Arc Suppressor has a high level of available sensitivity. It’s possible to adjust that sensitivity over a broad range, accommodating a great variety of sealing operations. In general, here are three beneficial rules to follow: 

  1. Increasing the area of the die requires lowered sensitivity.
  2. Increasing the thickness of the material requires higher sensitivity. 
  3. The use of the buffer requires higher sensitivity than if none is used at all. 


These Tests Ensure Your Arc Suppressor Is Set for Sealing Operations

Thermex-Thermatron designed this protective tool with an audible buzzer, ready to signal that the imminence or occurrence of an arc has called the Arc Suppressor into action. The buzzer will proceed to sound when the Arc Suppressor acts, persisting for the duration of the sealing cycle. At the close of the cycle, the Arc Suppressor’s buzzer will go off automatically. It’s possible to then immediately perform the next seal. 

To perform an Arc Suppressor self-test, you can operate the Arc Guard Test switch to the “UP” position. Because the switch is spring loaded, it must be held in the “UP” position. With the generator AC Power “ON,” and the press in the fully up position, the ARC light should illuminate. Additionally, the ARC signal buzzer should sound as long as this switch is held in the “UP” position. When this switch is released, the Arc Suppressor will automatically return to normal operation. 

Now, you can insert the work to be sealed. Adjust the sealing timer and power control to those settings, which experience suggests are appropriate for the particular operation. Set the sensitivity control to maximum clockwise. Now, you can bring down the press, attempting to perform the seal. The Arc Suppressor should act immediately or very early in the sealing cycle. If it does, and you see the seal looks incomplete, rotate the sensitivity control slightly counter-clockwise. Finally, replace the material and repeat the process. 

Thermex Thermatron How To Intelligently Use An Arc Suppressor Test Procedure

Sometimes, the sealing timer or the plate current limiting meter terminates that cycle before the Arc Suppressor acts. If so, and the seal is not completed, you must change one of the following: the original power, the plate current, or the timer adjustment. If more power is available, increase it. If not, you must increase the sealing time. Make the indicated adjustments, and if necessary, readjust the Arc Suppressor sensitivity control. 

Watch Out for These Conditions in a Sealing Cycle

When all adjustments are properly made, the sensitivity will be set for the maximum position. This allows you to obtain a satisfactory seal within the adjusted sealing time — without the Arc Suppressor being called upon to act. However, on those occasions when the imminence of an arc is sensed, the Arc Suppressor will be required while performing a seal. This condition may occur if you complete a seal before the completion of the timer cycle. 

Increased line voltage can lead to a surge in sealing power, which in turn can result in a seal’s early completion. Additionally, early completion of a seal can be due to one or more of the following:

  • An imperfection in the sealing material.
  • A bit of metal or dirt in the material. 
  • A burr on the die. 
  • Sealing off the edge of the material.
  • An imperfection or burned area on the buffer. 
  • If one of the above conditions prevails early in the sealing cycle, not only will the seal not be completed, but the work must be discarded. If it occurs towards the end of the cycle, however, the seal may still be satisfactory. 

On those occasions when the Arc Suppressor acts, damage to the die will either be slight or non-existent. Nonetheless, occasionally, carbonization may appear on the die or buffer. Before continuing to seal, it is advisable to clean the die and move the buffer. This way, you avoid the carbonized area falling beneath the seal. When a sufficient number of test seals have been performed, indicating that all adjustments are proper, you can lock the sensitivity control and proceed. 

The Consequences of Not Using an Arc Suppressor

An Arc Suppressor may be completely removed from a Thermatron sealer without affecting the actual seal quality. Nonetheless, operation without the Arc Suppressor is strongly discouraged. Even when sealing the best quality vinyl or urethane, there will be an occasional imperfection in the material that will result in an arc. If there is no Arc Suppressor, severe die damage may result from such an arc. 

During troubleshooting, if you want to remove the Arc Suppressor as an aid in localizing a problem, it is only necessary to jumper terminals 38 and 39, disconnecting wire 21 from the Arc Suppressor board to completely bypass the Arc Suppressor. In this situation, even though the Arc Suppressor may trigger and the buzzer may sound, the Arc Suppressor will have no effect on the RF output of the sealer. 

Safely Use an Arc Suppressor to Enhance Fundamental Processes

Proceed with caution and care, as the voltages inside the Arc Suppressor are dangerous. You will want to shut off all power before removing generator panels for Arc Suppressor servicing. Additionally, do not operate the Thermex-Thermatron generator unless you are certain the press is closed. Even though the Arc Suppressor high voltage capacitor has bleeder resistors, discharge this capacitor before servicing the Arc Suppressor. 

It’s crucial to understand how to properly operate an Arc Suppressor. Otherwise, you face losing efficiency on the production floor, leaving valuable equipment and materials vulnerable to hazardous accidents. Thermex-Thermatron’s knowledge as a leader spans multiple industries, making it possible for better engineered products in addition to a reduction in dangerous working conditions. 

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