What does Volt Free contact mean ?
and what does it have to do with Current Transdormers ?
Answer:
Volt-free and dry contact mean the same thing. If a control system supplier offers a dry contact for you to read as a status bit, then he is offering to close a contact (relay or contact output) that is nothing more that a stand-alone set of contacts with no voltage, current, or anything else impressed across the contact set. It becomes the user's responsibility to determine how to sense that contact closure. Usually you do this by putting a voltage on one side and sensing the voltage on a return line from the other side of the contact when it closes. Once you apply voltage to the contacts, it becomes a wet contact. You "wet" the contact with a sensible voltage level.
A proximity contact is a contact set that makes without any kind of direct coil or physical actuation of the contact set. Proximity contacts or switches are usually either optical devices that switch because a light beam is broken or completed, or in some cases magnetic switches are called proximity contacts. The contact set will open or close when a magnet gets close enough to cause the switch action like a door switch on a burglar alarm.
A volt free contact is a contact without any voltage on it. It is usually supplied in a system for other parties to use and they then supply their own voltage into their own system eg: to a BMS system.
I think the guys above talk about Relays, and not about Current Transformers as per your question.
Assume you want to measure the current in a circuitry. there are 2 standard ways
a) you put an Ampere Meter within the circuit
b) you put a small resistance within the circuit, and measure the voltage across that resistor.
Both methods mean that you have the circuit's voltage standing on your measurement device.
With a Current Transformer, you can avoid that. You have just a few (say 3 - 5) windings of thick wire on the primary side which goes in series in your circuit, and you have a good number of thin wire windings on the secondary side, with a voltage generated by the magnetic field of the current transformer, and which can be measured as a function of the current in the circuit.
So you measure a circuit current with a "Volt Free Contact".
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Answer:
Volt-free and dry contact mean the same thing. If a control system supplier offers a dry contact for you to read as a status bit, then he is offering to close a contact (relay or contact output) that is nothing more that a stand-alone set of contacts with no voltage, current, or anything else impressed across the contact set. It becomes the user's responsibility to determine how to sense that contact closure. Usually you do this by putting a voltage on one side and sensing the voltage on a return line from the other side of the contact when it closes. Once you apply voltage to the contacts, it becomes a wet contact. You "wet" the contact with a sensible voltage level.
A proximity contact is a contact set that makes without any kind of direct coil or physical actuation of the contact set. Proximity contacts or switches are usually either optical devices that switch because a light beam is broken or completed, or in some cases magnetic switches are called proximity contacts. The contact set will open or close when a magnet gets close enough to cause the switch action like a door switch on a burglar alarm.
A volt free contact is a contact without any voltage on it. It is usually supplied in a system for other parties to use and they then supply their own voltage into their own system eg: to a BMS system.
I think the guys above talk about Relays, and not about Current Transformers as per your question.
Assume you want to measure the current in a circuitry. there are 2 standard ways
a) you put an Ampere Meter within the circuit
b) you put a small resistance within the circuit, and measure the voltage across that resistor.
Both methods mean that you have the circuit's voltage standing on your measurement device.
With a Current Transformer, you can avoid that. You have just a few (say 3 - 5) windings of thick wire on the primary side which goes in series in your circuit, and you have a good number of thin wire windings on the secondary side, with a voltage generated by the magnetic field of the current transformer, and which can be measured as a function of the current in the circuit.
So you measure a circuit current with a "Volt Free Contact".
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