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Electronic Component Basics


Trombetta's electronic controls for industrial work solenoids control the magnitude of electrical drive applied to the coil during the pull-in and/or hold operation of the industrial work solenoid. All use Pulse Width Modulation (PWM) switching to achieve high operating efficiency. The particular methodology underlying the PWM scheme is what distinguishes the various families of industrial work solenoid controllers. Those distinctions are addressed in the section Electronic Control Families Features and Benefits. Feature enhancements may be incorporated into any of the controls to create a customized solution.

All Trombetta designs are robust, utilizing high quality components throughout, with considerable transient voltage suppression designed into each and every model.

All Trombetta electronic controls are designed with the same ultimate benefit of allowing the use of smaller industrial work solenoids than would otherwise be needed to generate the force necessary to perform a particular job. Smaller industrial work solenoids provide the end product designer with more mechanical design flexibility. The use of the controller maximizes the cost effectiveness of the industrial work solenoid while providing the often overlooked benefit of eliminating the need for more costly and fragile dual winding coils. A single coil under PWM control utilizes 100 percent of the winding at all times resulting in higher efficiency and cooler operation.

Trombetta's engineering team has decades of experience in both disciplines of industrial work solenoids and electronic controls affording our customers industrial work solenoid/control system designs that work together to optimize performance, size and cost.


Standard electronic controls are built utilizing type FR4 glass epoxy circuit boards. Through-hole board construction uses plated through holes. The standard controls are housed in cost efficient tooled housings and are encapsulated for physical and environmental toughness. These robust construction features allow the controls to be used in a wide array of applications.

When developing designs for customer specific applications Trombetta's engineering group works closely with the customer to determine the best packaging for the application. The final solution may involve a standard Trombetta housing, an existing customer enclosure or an enclosure purchased and possibly tooled specifically for the application.

Trombetta standard controls utilize screw type terminal blocks for input/output connections. This provides the greatest amount of flexibility over a broad range of applications. The terminal blocks are physically robust and utilize stainless steel screws for durability and corrosion resistance. When developing customized designs we work with the customer to determine the best connection scheme that meets the customers design specifications and cost constraints.

Electronic Controls Application Guidelines

Trombetta has learned that the following pieces of information are usually needed to correctly suggest electronic controls. If you are unsure of some of your application parameters, Trombetta engineers will help you in defining your system. Several standard electronic controls are available or Trombetta can design a custom unit to meet your specific needs.

1)  What is the system operating voltage and operating voltage range?
•  Consider not only the nominal but also the absolute high and low voltages under which the control must operate within the specification.
•  Are there extreme voltage conditions under which the control is not required to operate within specification, but is required to endure the conditions then recover and operate within specification?

2)  Are separate initiate controls needed or will primary power be switched?
•  If separate initiate controls are required, what control voltage will be used?
•  Is there need for more than one control input? (i.e. Will initiate be controlled through Boolean logic applied to multiple inputs?)
•  Is optical isolation of the control input(s) required?
•  Are there any control signal protocol issues?

3)  Is a single or dual action industrial work solenoid being controlled?
•  It is usually more economical to control both coils of a dual action industrial work solenoid with a single control equipped with dual outputs.

4)  Is it a pull only or a pull and hold application?
•  For applications with hold requirements, the hold force requirements and industrial work solenoid selection will need to be known to analyze the control system performance under all operating conditions.

5)  What is the required pull time?
•  The most extreme voltage and temperature conditions plus any mechanical factors that might affect solenoid and mechanism reaction time must be considered to accurately determine pull time.

6)  What is the ambient operating temperature range?
•  Be sure to consider not only the nominal conditions, but also the absolute high and low temperature conditions under which the control will be required to operate within specification.
•  Are there extreme temperature conditions under which the control is not required to operate within specification, but is required to endure the conditions then recover and operate within specification?
•  Are rapid temperature excursions expected (thermal shock)?

7)  What is the maximum operating rate and duty cycle requirement?
•  What is the maximum sustained on time?
•  What is the maximum sustained rate of on/off cycling?
•  Are any short duration bursts of on/off cycling anticipated? If so, characterize them.

8)  Are there any special considerations?
•  Regulatory standards or agency certifications?
•  Size or location restrictions?
•  Unusual operating conditions?
•  Shock, vibration, EMI, radiation?

Families Features and Benefits

Voltage Control Over-Energizer
Voltage Control Over-Energizers provide open loop control of voltage applied to the industrial work solenoid coil. No feedback is used to compensate for varied operating conditions. This type of electronic control incorporates an adjustable PWM (Pulse Width Modulation) signal to the industrial work solenoid to obtain the desired pull-in and hold performance. Some amount of operating voltage compensation can be designed into this type of control. Voltage Control Over-Energizers are the lowest cost over-energizer controls. A standard over-energized control can often be effectively paired with a standard industrial work solenoid to provide an efficient off-the-shelf system.

Current Regulating Over-Energizer
Current Regulating Over-Energizers exercise closed loop control over the industrial work solenoid coil. Actual coil current is sensed and regulated both during pull-in and holding modes of operation. The performance of the industrial work solenoid can be set via the specific control algorithms used in the current regulating scheme.

This type of control automatically compensates for significant variations in operating voltage and temperature. The end result is consistent pull/hold force under a variety of difficult operating conditions. Current Regulating Over-Energizer Controls allow the designer to always meet minimum force requirements while eliminating the possibility of the force becoming substantially greater than required. This reduces the risk of actuator induced apparatus damage.

When speed of operation is a critical factor, the system voltage should be taken into account. While Current Regulating Over-Energizer Controls will stabilize force over a broad range of operating conditions, the time of current in the industrial work solenoid is still affected by the system voltage. Trombetta's experience with this issue is used during the design and selection process for the controls.

Force Regulating Over-Energizer
The Force Regulating Over-Energizer takes industrial work solenoid control one step beyond what can be achieved with a Current Regulating Over-Energizer. The Force Regulating Over-Energizer compensates for external factors of voltage and temperature and adds closed loop compensation for plunger position thereby maintaining a near constant force throughout the working stroke.

This control is intended for use with short stroke, high force industrial work solenoids, particularly those utilizing flat plate or T type Armatures. The Force Regulating Over-Energizer Control is particularly beneficial to such applications as diaphragm pumps, brakes and clutches. For even more control benefit, a controlled rate of force application can be programmed into the control algorithm.

Feature Enhancements
Trombetta has the capability to design in advanced customized features to help meet specific system requirements. Examples of these features include:
•  Ability to accommodate a very wide range of system operating voltages. Ratios of 5 to 1 and greater have been accommodated.
•  Multiple and optically isolated inputs as control input signals.
•  Added logic functions such as timers and Boolean operators to monitor various external signals.
•  Customized physical configuration and packaging.
•  Multiple output controls on a single circuit board.
•  Customized input/output connectors.

Non-Industrial Work Solenoid Related Electronic Controls
Trombetta has the technology and experience to develop custom controls for various non-industrial work solenoid applications. Trombettas experience with various PWM (Pulse Width Modulation) control techniques and control algorithms, as well as our experience in diverse and often harsh electrical environments, provides benefits in a variety of applications. Any application where variable output is needed to control, adjust or compensate within the system is an application for a custom controller. Various input parameters (voltage, current, resistance, temperature) can be monitored to control the output and add to the flexibility of the controller.