Encountering a new situation, I found myself dealing with a 120v output card that controls a motor contactor and overloads. After setting the output, the motor started but eventually overamperage caused the overloads to trip, shutting off the motor. With A1 receiving 120v and A2 using the neutral with normally closed contacts, I observed that removing the 120v led to different voltage readings depending on the connections. Upon turning off the output, I discovered that testing from A1 yielded 120v when grounded or connected to the main neutral terminals. However, when connected to the normally closed terminals (which loop back to the main neutral terminal), the voltage was 0. Surprisingly, this occurred without resetting the overload. After resetting the overload, the voltage readings returned to what was expected. This led me to wonder if a coil can retain voltage during an overload situation. I have been unable to find any information on this phenomenon. Any insights would be greatly appreciated. Thank you.
It seems like the neutral wire of the 120 volt source or feed you are using may not be properly grounded. Make sure your electrical system is properly grounded to prevent any potential issues.
Mavrick inquired whether a coil can retain voltage during overload situations, similar to a capacitor. However, nothing can store an AC voltage in that manner. Mavrick further described a scenario where A1 on the coil was receiving 120v and A2 was connected to the neutral, causing the circuit to open. Surprisingly, even after removing the 120v input, connecting A1 to ground or the main neutral terminals resulted in 120v readings, while connecting to the normally closed terminals resulted in 0 volts. This phenomenon occurred without resetting the overload, leading to suspicions of induced or capacitively coupled ("phantom") voltage. Upon resetting the overload, the voltage readings returned to the expected zero. It was suggested that the initial readings could be attributed to induced signals, as the coil effectively acted as an antenna. To verify the voltage readings, using a DMM with low impedance input was recommended.
If you are using a triac output card, a common issue is reading 120V when there is no load due to leakage current through the triac. In this case, your meter may not provide sufficient load to accurately measure the voltage.
In the event that a contactor has three overloads, it is essential to disconnect the power and carefully remove them. Press the overload reset button before inserting the new overloads in a straight manner. Take note of the type of output card in use and proceed with caution when removing wires from the output terminal. It is important to understand the circuit, as power is typically applied to the normally closed contact before passing through the coil and connecting to the neutral output. This signifies a sinking output, not a sourcing one. It is advisable to be cautious and follow these steps carefully.
Eric Nelson explained that when testing a triac output card, a reading of 120V may be displayed if there is no load due to leakage current through the triac. In this situation, a meter alone may not provide enough of a load to accurately measure the output voltage. This information is essential for troubleshooting and ensuring accurate readings from the card.
This is an interesting observation. Typically, a coil doesn't retain voltage; the energy stored in a power coil is quickly dissipated as soon as the current flow is interrupted in an event like an overload trip-off. However, the phenomenon you've described could potentially be related to "phantom" or "ghost" voltages, which can be detected when testing open lines even when the circuit is isolated. This phenomenon is commonly seen when using high-impedance testing equipment, as they can pick an electromagnetic field existing in an open circuit, which may result in fluctuating readings. I'd suggest checking your testing equipment or trying with a low impedance tester to see if you get a consistent result.
This is a fascinating occurrence you've come across. In typical circumstances, a coil shouldn't retain voltage after cutting the power supply. Although, it's important to remember that coils can create induced voltages due to collapsing magnetic fields, this happens when the circuit is abruptly interrupted or de-energized. However, the scenario you've described does make me wonder if there's something else going on. There might be some stray voltages present, or perhaps a faulty grounding. Alternatively, you might want to check if the overloads are functioning properly, as a malfunction might give erroneous readings. You could also consider the quality of your measuring instrument in this situation. Sometimes, we tend to oversee these possibilities. Let us know if you solve this puzzle.
It sounds like you've stumbled upon an interesting situation here! You've aligned with a couple of key electrical principles, primarily the difference between voltage and current. Specifically, coils can't retain voltage, but they can retain a magnetic field. When the overloads tripped, it interrupted the current, causing the magnetic field to collapse and leading to an "induced" voltage due to the effect called inductance. So technically, it's not that the coil is "retaining" voltage, but rather the changing magnetic field is inducing a voltage. When you reset the overload, you likely re-established a steady state condition and therefore no longer observed voltage across the open coil. Just a theory, but it could explain what you observed!
It seems like you've stumbled upon a fascinating scenario here. Based on your observations, it does seem plausible that the coil is holding some charge even with an overload. However, what's likely happening is that the overloads interfere with the normal voltage path but don't cut the power off completely. Essentially, when the system is overloaded, the connection between A1 and main neutral terminal remains active, hence the 120v reading. However, the connection between A1 and your normally closed contacts is interrupted despite looping back to the main neutral terminal, hence a zero reading. Once you reset the overload, the pathways revert back to their original state, resulting in normal voltage readings. That's just my take on it. We're delving into potentially new territory here, it would be great to know what others think about this.
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Answer: - In the scenario described, the user observed unexpected voltage readings when testing the contactor coil connections. This led to the question of whether a coil can retain voltage during an overload situation. - Answer: Based on the user's experience, it seems that in certain conditions, such as during an overload situation, the contactor coil may retain voltage. Resetting the overload helped return the voltage readings to normal.
Answer: - The user mentioned that the motor started but eventually overamperage caused the overloads to trip, shutting off the motor. Understanding why this occurred is crucial for troubleshooting and preventing future issues. - Answer: Overloads are designed to protect the motor from excessive current, which can lead to overheating and damage. When the motor draws more current than the overloads are rated for, they trip to prevent further damage.
Answer: - The user observed that removing the 120v input led to different voltage readings depending on how the contactor coil connections were tested. Understanding why the voltage readings varied can provide insights into the electrical behavior of the system. - Answer: The varying voltage readings when testing the contactor coil connections could be attributed to how the circuit is designed and how different connections affect the flow
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