The subject matter described herein relates generally to electrical connectors and, more particularly, to electrical connectors having a resistor.
Existing electrical connectors include ground contacts and power contacts extending therefrom. The power contacts are configured to carry electrical power between the connector and a corresponding mating connector. Generally, connectors and mating connectors are coupled when the power signal is inactive. Accordingly, such “cold mating” does not present problems with power surges across the connectors. However, some connectors and mating connectors may be “hot mated” at a time when a power signal is flowing through one or more of the connectors. Whenever more than a few volts and/or a few amps are available to an interconnection as it is separated or mated, there can be damage to the contacts and connector as well as risk to the operator if the energy is sufficiently high. In spite of this risk, there are many situations that require hot mating between connectors.
Some existing connectors utilize an auxiliary contact with a series PTC (positive temperature coefficient) device. The PTC device can provide protection against damaging results when separating energized DC circuits with inductive and resistive loads. In such a device, a ground contact carries the main current and makes the connection first and separates last. A power contact is the second main current carrying member and makes the connection last and separates first. The auxiliary contact is in series with the PTC device. The auxiliary contact and the PTC device are in parallel with the main power contact. The auxiliary contact provides an intermediate timed connection and separation. As the connector is separated, the main power contact separates first. There is essentially no voltage across this interface as it separates because the voltage is shunted by the auxiliary contact and PTC device. Without sufficient voltage difference, there can be no arcing and therefore no contact damage. During the time the connector continues to separate but before the auxiliary contact separates, the PTC device switches to a high resistance state because the load current now flows through the PTC device. When the auxiliary contact finally separates there is no current flowing through the connection, again preventing a damaging arc at the interface. This arrangement provides protection against the severely damaging plasma arc that can develop at a separating energized interface. This is true for all resistive and inductive loads.
However, PTC devices do not provide protection for systems with capacitive loads. For capacitive loads a significant voltage difference is not normally encountered at separation. With inductive and resistive loads there is generally little damage to the contacts if they have sufficient mass and are mated at an adequate velocity. Existing connector designs provide adequate protection for inductive and resistive loads during separation and mating, but do not provide adequate protection from capacitive loads during mating.
A need remains for a connector that can be hot mated to a mating connector supplying a capacitive load without damaging the contacts or connector.
In one embodiment, an electrical connector is provided. The electrical connector includes a body having a terminating end and a mating end. A power contact extends from the mating end of the body. The power contact is configured to be engaged by a power contact of a mating connector connected to a predominantly capacitive load. An auxiliary contact extends from the mating end of the body. The auxiliary contact is coupled in series with a resistor. The auxiliary contact configured to be engaged by an auxiliary contact of the mating connector. The auxiliary contact in series with the resistor is configured to engage the mating connector before the power contact to resist a surge current due to the capacitive load from the mating connector.
In another embodiment, an electrical connector is provided. The electrical connector includes a body having a terminating end and a mating end. A power contact extends from the mating end of the body. The power contact is configured to be engaged by a power contact of a mating connector supplying a capacitive load. An auxiliary contact extends from the mating end of the body. The auxiliary contact is configured to be engaged by an auxiliary contact of the mating connector. The auxiliary contact extends from the mating end of the body further than the power contact. The auxiliary contact is configured to engage the mating connector before the power contact. A resistor is electrically coupled in series to the auxiliary contact and configured to resist the capacitive load of the mating connector. The resistor is electrically coupled in parallel to the power contact.
In another embodiment, an electrical connector is provided. The electrical connector includes a body having a terminating end and a mating end. A power contact extends from the mating end of the body. The power contact is configured to engage a power contact of a mating connector carrying a capacitive load. An auxiliary contact extends from the mating end of the body. The auxiliary contact is configured to engage an auxiliary contact of the mating connector before the power contact engages the power contact of the mating connector. A negative temperature coefficient (NTC) device is electrically coupled to the auxiliary contact to limit a surge current of the capacitive load from the mating connector. The NTC device is configured to provide a high resistance to the capacitive load when the auxiliary contact initially engages the mating connector. The resistance of the NTC device is configured to decrease as the NTC device is heated by the charging current of the capacitive load.
The foregoing summary, as well as the following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.
The connector 102 includes a body 106 having a terminating end 108 and a mating end 110. The terminating end 108 receives wires, cables, or the like from an electrical device (not shown). In particular, the terminating end 108 receives a ground wire 112 and a power wire 114 of the electrical device. A ground contact 116 is positioned within the body 106. The ground contact 116 includes a terminating end 118 and a mating end 120. The terminating end 118 is joined to the ground wire 112. The mating end 120 of the ground contact 116 extends from the mating end 110 of the body 106. A power contact 122 is also positioned within the body 106. The power contact 122 includes a terminating end 124 and a mating end 126. The terminating end 124 of the power contact 122 is joined to the power wire 114. The mating end 126 of the power contact 122 extends from the mating end 110 of the body 106. The terminating end 124 of the power contact 122 includes a resistor 140 joined thereto. The resistor 140 may be a fixed resistor and/or a negative temperature coefficient (NTC) device.
An auxiliary contact 134 is positioned within the body 106. The auxiliary contact 134 includes a terminating end 136 and a mating end 138. The terminating end 136 of the auxiliary contact is joined to the resistor 140 that is coupled to the terminating end 124 of the power contact 122. The mating end 138 of the auxiliary contact 134 extends from the mating end 110 of the body 106.
The mating connector 104 includes a body 150 that is configured to couple to the body 106 of the connector 102. The mating connector body 150 includes a terminating end 152 and a mating end 154. The mating end 154 of the mating connector 104 is configured to couple to the mating end 110 of the connector 102. The terminating end 152 of the mating connector 104 receives wires, cables, or the like from an electrical device (not shown). In one embodiment, the terminating end 152 of the mating connector 104 receives a ground wire 156 and a power wire 158 of the electrical device.
A ground contact 160 is positioned within the body 150 of the mating connector 104. The ground contact 160 includes a terminating end 162 and a mating end 164. The terminating end 162 receives the ground wire 156. The mating end 164 of the ground contact 160 extends from the mating end 154 of the body 150. The mating end 164 of the ground contact 160 of the mating connector 104 is configured to couple to the mating end 120 of the ground contact 116 of the connector 102.
A power contact 166 is positioned within the body 150 of the mating connector 104. The power contact 166 includes a terminating end 168 and a mating end 170. The terminating end 168 of the power contact 166 receives the power wire 158. The mating end 170 of the power contact 166 extends from the mating end 154 of the body 150. The mating end 170 of the power contact 166 of the mating connector 104 is configured to couple to the mating end 126 of the power contact 122 of the connector 102.
An auxiliary contact 172 is positioned within the body 150 of the mating connector 104. The auxiliary contact 172 includes a terminating end 174 and a mating end 176. The terminating end 174 is electrically coupled to the terminating end 168 of the power contact 166 (as illustrated in
The mating connector 104 couples to the connector 102 to direct current (DC) power between the mating connector 104 and the connector 102. When the mating connector 104 is joined to the connector 102, the ground contacts 116 and 160 are coupled first to establish a ground connection between the mating connector 104 and the connector 102. Next, the auxiliary contacts 134 and 172 are joined. The auxiliary contact 134 of the connector 102 receives the capacitive load of the mating connector 104 from the auxiliary contact 172 of the mating connector 104. The auxiliary contact 134 of the connector 102 is electrically coupled to the resistor 140. The resistor 140 resists the capacitive load of the mating connector 104 by reducing the charging current of the capacitive load flowing between the mating connector 104 and the connector 102. In an embodiment where the resistor 140 is a NTC device, the resistor 140 gradually increases a voltage of the capacitive load in the connector 102 by gradually shifting from a high resistance to a low resistance. After the auxiliary contacts 134 and 172 mate, the current flowing through the resistor 140 causes the resistor 140 to change from a high to a lower resistance value. The initial high resistance value limits an initial current surge to a safe level. Reducing the resistance increases the charging rate to get the capacitive load to a supply voltage by the time the power contacts 122 and 166 touch.
Once the supply voltage is reached, the power contacts 122 and 166 may be joined without creating a damaging current surge between the connector 102 and the mating connector 104. The resistor 140 enables hot-mating of the connector 102 and the mating connector 104 without creating a surge between the connector 102 and the mating connector 104. The resistor 140 prevents possible damage to the connectors 102 and 104, as well as the electrical devices coupled to the connector 102 and the mating connector 104. The resistor 140 also prevents potential injury to an operator joining the connector 102 and the mating connector 104.
The auxiliary contact 134 has a length 142 that is defined between the terminating end 136 and the mating end 138 of the auxiliary contact 134. The length 142 of the auxiliary contact 134 may be greater than, less than, or equal to the length 128 of the ground contact 116. The length 142 of the auxiliary contact 134 may be greater than, less than, or equal to the length 130 of the power contact 122. The auxiliary contact 134 is positioned within the body 106 so that the mating end 138 of the auxiliary contact 134 extends further from the mating end 110 of the body 106 than the mating end 126 of the power contact 122. The mating end 138 of the auxiliary contact 134 extends a distance 144 further from the mating end 110 of the body 106 than the mating end 126 of the power contact 122. The auxiliary contact 134 is positioned within the body 106 so that the mating end 120 of the ground contact 116 extends further from the mating end 110 of the body 106 than the mating end 138 of the auxiliary contact 134. The mating end 120 of the ground contact 116 extends a distance 146 further from the mating end 110 of the body 106 than the mating end 138 of the auxiliary contact 134.
The ground contact 116 of the connector 102 includes a terminal 180 at the terminating end 118 of the ground contact 116. The ground wire 112 is positioned within the terminal 180. The terminal 180 is clamped into a closed position to retain the ground wire 112 and create an electrical connection between the ground wire 112 and the ground contact 116.
The power contact 122 includes the resistor 140 joined to the terminating end 124 thereof. An intermediate contact 182 extends from the resistor 140 to the power contact 122 to couple the resistor 140 in parallel with the power contact 122. The power contact 122 is also joined to the power wire 114 to create an electrical connection between the power contact 122 and the power wire 114.
The auxiliary contact 134 includes a terminal 184 at the terminating end 136 thereof. The terminal 184 is coupled to a resistor lead 186. The resistor lead 186 extends between the auxiliary contact 134 and the resistor 140 to electrically couple the auxiliary contact 134 and the resistor 140 in series.
The ground contact 160 of the mating connector 104 includes a terminal 188 at the terminating end 162 thereof. The terminal 188 receives the ground wire 156 of the electrical power source. The terminal 188 is crimped or otherwise secured to the ground wire 156 to retain the ground wire 156 and create an electrical connection with the ground wire 156.
The power contact 166 includes a terminal 190 at the terminating end 168 thereof. The terminal 190 receives the power wire 158 of the electrical power source. The terminal 190 is crimped or otherwise secured to the power wire 158 to retain the power wire 158 and create an electrical connection between the power wire 158 and the power contact 166.
The auxiliary contact 172 includes an intermediate contact 192 at the terminating end 174 thereof. The intermediate contact 192 extends between the auxiliary contact 172 and the power contact 166 to electrically couple the auxiliary contact 172 and the power contact 166. The auxiliary contact 172 and the power contact 166 are electrically coupled in parallel.
The auxiliary contacts 172 and 134 in series with the resistor 140 are electrically coupled in parallel with the power contacts 122 and 166, respectively, so that the capacitive charge of the mating connector 104 may be directed through the auxiliary contacts 172 and 134 and resistor. The resistor 140 controls the charging current to the capacitive load to increase a charging rate and get the capacitive load to a supply voltage by the time the power contacts 122 and 166 touch. Once the supply voltage is reached, the power contacts 122 and 166 may be joined without creating a surge between the connector 102 and the mating connector 104.
When the mating connector body 610 is received within the connector body 606, the detents 614 and 616 engage one another as illustrated in
Graph 300 includes a second line 310 representing the voltage in a connector having an auxiliary contact joined to a fixed resistor, for example a fixed 25 ohm resistor. The fixed resistor resists the capacitive load of the mating connector so that the voltage of the capacitive load is gradually received by the connector. In particular, the connector initially receives 0 V from the mating connector. The auxiliary contacts become engaged at approximately 1 ms at point 312. The resistor creates a gradual voltage increase in the connector between point 312 and point 314 (approximately 3 ms). The resistor increases the voltage in the connector between point 312 and 314 to approximately 300 V. Accordingly, when the power contacts engage at point 308, the voltage in the connector only jumps 100 volts from 300 V to 400 V.
As illustrated in
The graph 350 includes a first line 356 representing the current through a connector that does not include a resistor and auxiliary contacts. As illustrated in line 356, the connector does not receive any current from the capacitive load of the mating connector until point 358 after 8 ms. Point 358 represents the time at which the power contacts of the connector and the mating connector become engaged. At point 358, the connector experiences a spike in current from 0 A to approximately 55 A. Such a current spike may be damaging to the connector. Moreover, the spike in current may result in injury to an operator joining the connector and the mating connector.
The graph 350 includes a second line 360 representing the current through a connector having a fixed resistor, for example a fixed 25 ohm resistor, and an auxiliary contact. At point 362, at approximately 1 ms, the auxiliary contacts of the connector and the mating connector are joined. At point 362, the connector experiences an increase in current to approximately 10 A. The current then reduces at point 364 to approximately 5 A. At point 358, the power contacts are joined and the current in the connector increases to approximately 15 A before being reduced to approximately 6 A.
As illustrated in
Compared to line 306 in
Compared to line 356 in
It should be noted that there is no danger of generating a damaging plasma arc when the connection between the connector and the mating connector is separated at sufficient velocity as controlled by the housing design. There will be no significant voltage between the separating contacts because the capacitive load will have stored electrical energy that takes some time to deplete.
The connector assembly has a further advantage over the use of an NTC internal to a capacitive load. When NTC devices are used for surge suppression they are simply connected in series with that load. Since the NTC device does not reduce to an insignificant resistance there will always be a loss across them. There is also heat generated by that loss. The connector assembly eliminates both the loss and the heat because the NTC device is shunted by the main power contact when the connector is fully engaged. The connector assembly improves system efficiency as well as reducing the cooling load.
It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments of the invention without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments of the invention, the embodiments are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.
This written description uses examples to disclose the various embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice the various embodiments of the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if the examples have structural elements that do not differ from the literal language of the claims, or if the examples include equivalent structural elements with insubstantial differences from the literal languages of the claims.
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