CN201928001U - Open circuit protector of current transformer - Google Patents
Open circuit protector of current transformer Download PDFInfo
- Publication number
- CN201928001U CN201928001U CN2011200094123U CN201120009412U CN201928001U CN 201928001 U CN201928001 U CN 201928001U CN 2011200094123 U CN2011200094123 U CN 2011200094123U CN 201120009412 U CN201120009412 U CN 201120009412U CN 201928001 U CN201928001 U CN 201928001U
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- current
- current transformer
- circuit protector
- phase
- open circuit
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Abstract
The utility model provides an open circuit protector of a current transformer, comprising a zinc oxide resistor disc and current relays which are serially connected with each other. During usage, the open circuit protector of the current transformer is parallelly connected to two ends of a secondary winding loop of the current transformer. The utility model further provides an open circuit protector of a current transformer, which realizes three-phase power transmission and comprises three zinc oxide resistor disc and current relay serial connection branches, and each branch is respectively parallelly connected to two ends of each of secondary winding loops of A-phase, B-phase and C-phase current transformers of a three-phase power transmission line. An indicator lamp on each branch is lightened when the secondary winding loop of the corresponding-phase current transformer is in open circuit. Output joints of the current relays are normally open joints, and two ends of each of the three normally open joints are respectively connected to a first wiring terminal and a second wiring terminal. The open circuit protector has the advantages that when secondary windings of the current transformer are in open circuit, voltage is absorbed and reduced to a value below safe voltage, and accordingly personnel and equipment safety can be ensured.
Description
[technical field]
The utility model relates to the electric equipment that uses in the electric power system, specifically relates to a kind of protector of current mutual inductor.
[background technology]
Current transformer is called for short TA; be to be used for big electric current is converted to scale the electric equipment of little electric current in the electric power system; the little electric current of regulation ratio conversion is offered various meterings, relaying protection, reaches the automatics use; and with electrical secondary system and high voltage installation isolation; thereby guarantee the person and device security, schematic diagram as shown in Figure 1.Umber of turn of current transformer is few, the secondary winding number of turn is more, the normal operation of current transformer as shown in Figure 1, short-circuit condition is approached in the secondary winding loop when operate as normal, be that impedance Z approximates zero, impedance Z both end voltage Uz=I2*Z=0 will produce dangerous overvoltage when open circuit appears in the secondary winding loop.Secondary winding induces overvoltage (peak value can reach several kilovolts even volt up to ten thousand), and serious threat personal safety and metering, protective device operation cause the secondary insulation breakdown; and make the supersaturation of current transformer magnetic circuit; the iron core heating burns out current transformer, also may initiation fire.At present in the electric power system also not about the protective device of secondary winding in current transformer open circuit, therefore design and a kind ofly be used for protecting the protector of current mutual inductor of the person and device security to become the problem of needing solution in the present industry badly.
[summary of the invention]
One of technical problem to be solved in the utility model is to provide a kind of can monitor the secondary winding in current transformer open circuit, thereby can protect the current transformer open-circuit protector of the person and device security.
Two of technical problem to be solved in the utility model is to provide a kind of current transformer open-circuit protector of three-phase power transmission.
The utility model is what one of to solve the problems of the technologies described above by the following technical programs: a kind of current transformer open-circuit protector; a zinc oxide resistance sheet and a current relay of comprising series connection; during use, this current transformer open-circuit protector is connected in parallel on the two ends in secondary winding in current transformer loop.
Described current relay is an overcurrent relay.
The utility model be solve the problems of the technologies described above by the following technical programs two: a kind of current transformer open-circuit protector of three-phase power transmission; comprise three zinc oxide resistance sheets and current relay series arm, each branch road is connected in parallel on the two ends in three phase line A, B, C phase current mutual inductor secondary winding loop respectively.When opening a way in this phase current mutual inductor secondary winding loop, lights every branch road indicator light.
The contact of each current relay is normal opened contact, and the two ends of three normal opened contacts are connected to first binding post and second binding post.
Described current relay is an overcurrent relay.
The utility model has the advantages that: when secondary winding in current transformer is opened a way, overvoltage is absorbed and reduce to below the safe voltage, thereby can guarantee to protect the person and device security.And reporting the monitor staff immediately, the monitor staff can notify the professional to handle open circuit rapidly.
[description of drawings]
Fig. 1 is the normal operation logic figure of monophase current instrument transformer;
Fig. 2 is the utility model current transformer open-circuit protector and application structure schematic diagram;
Fig. 3 is the current transformer open-circuit protector external form figure that is applied to three-phase power transmission;
Fig. 4 is the contact point signal schematic diagram.
[embodiment]
The utility model will be further described in conjunction with the embodiments with reference to the accompanying drawings, so that those skilled in the art can better understand the utility model and being implemented, but illustrated embodiment is not as to qualification of the present utility model.
See also Fig. 2; the utility model current transformer open-circuit protector comprises zinc oxide (ZnO) resistor disc and a current relay (LJ) of series connection; during use; this current transformer open-circuit protector is in parallel with the impedance in secondary winding in current transformer loop; the overvoltage that can eliminate danger guarantees to protect the person and device security.
The design principle of this current transformer open-circuit protector is as described below.
The current transformer open-circuit protector utilizes zinc oxide resistance sheet (ZnO) to absorb overvoltage, and is very little or during less than its continuous operating voltage, zinc oxide resistance sheet is in cut-off state, presents high resistance when the zinc oxide resistance sheet both end voltage.When invading greater than the overvoltage of its continuous operating voltage, its resistance sharply reduces.When the zinc oxide resistance sheet two ends return to continuous operating voltage when following, zinc oxide resistance sheet returns to cut-off state again, presents high resistance.Utilize current relay (LJ) action, junction closure, generating current transformer open circuit signaling.Current relay is selected overcurrent relay for use, can set setting value, when current relay by electric current when setting current setting, current relay is failure to actuate, contact is not closed, does not have any signal and sends.When current relay by electric current when setting current setting, current relay action, junction closure, generating current transformer open circuit signaling.
The operation principle that the current transformer open-circuit protector is complete is as described below.
Short-circuit condition is being approached in the secondary winding in current transformer loop during operate as normal, and promptly impedance Z approximates zero, impedance Z both end voltage Uz=I2*Z=0.Current relay (LJ) impedance Z 1 approximates zero, and zinc oxide resistance sheet (ZnO) both end voltage is very for a short time to approximate zero.Zinc oxide resistance sheet is in cut-off state, presents high resistance.Current relay approximates zero by electric current is very for a short time, is significantly smaller than the setting current setting, and current relay is failure to actuate, and contact is not closed, does not have any signal and sends.When open a way in the secondary winding in current transformer loop, zinc oxide resistance sheet (ZnO) two ends will produce overvoltage immediately.Overvoltage numerical value is much larger than zinc oxide resistance sheet (ZnO) continuous operating voltage numerical value.Its resistance sharply reduces.Overvoltage is absorbed and reduce to below the safe voltage, thereby can guarantee to protect the person and device security.Much larger than setting current setting, current relay (LJ) moves current relay by electric current simultaneously, junction closure, generating current transformer open circuit signaling.Can report monitor staff TA open circuit immediately, the monitor staff can notify the professional to handle the TA open circuit rapidly.
Electric system AC electricity transmission is three-phase power transmission; every circuit is A; B; the C three-phase power transmission; three current transformers of every every end installing of circuit; three current transformers are one group; TA open-circuit protector of every current transformer installing; three TA open-circuit protectors of three current transformer installings; the TA open-circuit protector external form of design as shown in Figure 3; LJ1 wherein; LJ2; LJ3 is three current relays; LJ1; LJ2; the circle of LJ3 below is respectively the A indicator light of opening a way mutually; the B indicator light of opening a way mutually; the C indicator light of opening a way mutually; when certain phase TA open circuit, this phase indicator light is bright.The zinc oxide resistance sheet (ZnO) of corresponding each current relay is installed in device inside."+-" be LJ1, LJ2, LJ3 current relay 220V DC power supply.A1 A2, B1 B2, C1 C2 are connected to the binding post of A phase, B phase, C phase current mutual inductor for each phase TA open-circuit protector.X1X2 is TA circuit-opening contacts signal terminal that sends to Surveillance center, principle as shown in Figure 4, LJ11, LJ22, LJ33 are normal opened contact, when A, B, the arbitrary phase TA open circuit of C, LJ11, LJ22, LJ33, the one junction closure, the X1X2 binding post is sent out the TA open circuit signaling to Surveillance center.
Claims (5)
1. a current transformer open-circuit protector is characterized in that: comprise a zinc oxide resistance sheet and a current relay of series connection, during use, this current transformer open-circuit protector is connected in parallel on the two ends in the secondary winding loop of current transformer.
2. current transformer open-circuit protector as claimed in claim 1 is characterized in that: described current relay is an overcurrent relay.
3. the current transformer open-circuit protector of a three-phase power transmission, it is characterized in that: comprise three zinc oxide resistance sheets and current relay series arm, each branch road is connected in parallel on the two ends in three phase line A, B, C phase current mutual inductor secondary winding loop respectively.
4. the current transformer open-circuit protector of three-phase power transmission as claimed in claim 3, it is characterized in that: the contact of each current relay is normal opened contact, and the two ends of three normal opened contacts are connected to first binding post and second binding post.
5. as the current transformer open-circuit protector of claim 3 or 4 described three-phase power transmissions, it is characterized in that: described current relay is an overcurrent relay.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011200094123U CN201928001U (en) | 2011-01-13 | 2011-01-13 | Open circuit protector of current transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011200094123U CN201928001U (en) | 2011-01-13 | 2011-01-13 | Open circuit protector of current transformer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201928001U true CN201928001U (en) | 2011-08-10 |
Family
ID=44431836
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011200094123U Expired - Fee Related CN201928001U (en) | 2011-01-13 | 2011-01-13 | Open circuit protector of current transformer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201928001U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104898006A (en) * | 2014-03-04 | 2015-09-09 | 国家电网公司 | Current transformer secondary side open circuit anticipation device |
| CN107315157A (en) * | 2017-08-04 | 2017-11-03 | 国网江苏省电力公司无锡供电公司 | A kind of current transformer circuit supervision fail alarm detector and current transformer device |
-
2011
- 2011-01-13 CN CN2011200094123U patent/CN201928001U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104898006A (en) * | 2014-03-04 | 2015-09-09 | 国家电网公司 | Current transformer secondary side open circuit anticipation device |
| CN107315157A (en) * | 2017-08-04 | 2017-11-03 | 国网江苏省电力公司无锡供电公司 | A kind of current transformer circuit supervision fail alarm detector and current transformer device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110810 Termination date: 20120113 |