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Trometta Solenoids, DC Contactors and Switches
DC Contactors Basic Operation
FAQ: faq-solenoid.cfm
Q: What do the Wire Colors Mean?
A: White - pull coil/high current
      Red - hold coil/low current
      Black - ground


Q: What if I have a 2-wire Solenoid?
A: Non polarity sensitive. Either wire can be hooked up positive or ground.

Q: What is the difference between a Pull or Push Solenoid?
A: Linear solenoids are designed to pull the plunger with sufficient force to move a connecting load. The same principle can be applied to perform push operation by adding a non-magnetic rod or push bar to the plunger and extending it through the opposite end of the solenoid.

Q: What is Stroke?
A: Stroke is the airgap between the point where the plunger movement begins and where it seats against a stop. Solenoids will operate at any stroke up to maximum as long as the plunger is seated.. Design for the shortest possible stroke for greatest efficiency and minimum wear to prolong service life. Maximum stroke is the longest distance you can effectively operate the solenoid.

Q: What is Force?
A:You need to make sure your solenoid ratings are appropriate for the worst case scenario. Force curves are in ideal conditions. Low voltage, temperature, side load, vibration can all reduce force output of solenoid including the life of the solenoid.

Force is measured as pounds over the travel distance (i.e.. 12 lbs at 1 inch)


Q: Linkage Alignment Hookup?
A: The solenoid plunger and the load should be linked in a straight line. Plunger side force results in excess wear of the plunger, guide and a decrease in net force output and life of solenoid.

Q: What is a Control Module?
A: Trombetta's control module functions as a high current remote coil switching/time delay relay system. When utilized with Trombetta's 3-wire solenoid, it provides a system that can upgrade applications that previously required an internally switched solenoid and/or elaborate wiring methods. Can also be used with 2-wire solenoids externally switched solenoids.

Q: Duty Cycle?
A: Specifies the length of time a solenoid can be electrically energized and de-energized. There are three categories: Continuous - solenoid on without interruption for long periods of time - usually 2 minutes or longer. Intermittent - coil in energized for a short time, usually not more than 30 seconds, and allowing sufficient cooling time before the next operation. Pulse - coil is energized just long enough for the plunger to seat and then must be allowed to cool sufficiently before the next operation.

Formula: ON time/(ON + OFF) time

Example - If a solenoid is energized 1 second out of 4 seconds, the duty cycle is 1/(1+3) = ¼ or 25%.


Q: Rapid Cycling?
A: Normally, more heat is generated during the actuation period. When rapid cycling occurs, the increase in heat may be more than the solenoid can dissipate even for a continuous duty coil. This will result in reduced performance and could lead to solenoid failure. Generally our solenoids are not designed to operate more than once in 10 seconds.

Q: Operating temperature?
A: Coils are designed for a temperature rise of 85 C maximum plus the ambient temperature resulting in total operating temperature. Insulation materials must be selected to provide adequate protection from overheating. Higher temperature insulations are available for extreme operating temperatures.

Q: Environment Protection?
A:Standard Trombetta units are designed to meet normal industrial application operating conditions. Additional protection of exposed surfaces may be required for unusual situations. Examples are humidity, water splash, oil immersion or spray, sand, dust, dirt, shock, vibration, and radiation.

Q: Circuit Protection?
A: A slow blow fuse must be installed in the positive lead (+) to protect the solenoid from burn-out should jammed linkage or other obstruction occur. The following sizes are recommended fro all models:

Buss fuse:
  • MDL 10 for 12 VDC systems
  • MDL 5 for 24 VDC systems
  • *consult Factory for appropriate fusing by family size


Q: What size lead wire and length of lead is required?
A: Wiring requirements vary widely by application and industrial work solenoid type. The table below is provided as an example which is applicable to the majority of Trombetta's engine related industrial work solenoids. If you are uncertain about your wiring needs please consult with our Inside Sales Manager.

Solenoid Rated Voltage Max. lead length for all leads (in feet) wire/gauge size
18GA 16GA 14GA 12GA 10GA 8GA 6GA
P/Q610
D610
12 VDC 4 6 9.5 15 24 38 60
24 VDC 15 24 38 60 96 150 240
P/Q612/613
D613/513
12 VDC 2.5 4 6 10 16 25 40
24 VDC 10 16 25 40 64 100 160
*Incorrect wire size will result in reduced performance.


8111 N. 87th Street
Milwaukee WI, 53224
P:414-410-0300
F:414-355-3882