Proposal of Circuit Breaker Type Disconnector for Surge Protective Device

Transcription

1 Poposal of Cicuit Beake Type Disconnecto fo Suge Potective Device MASAO SHIBAYAMA, HITOSHI KIJIMA Polytechnic Univesity Ogawanishi, Kodaia, Tokyo, JAPAN Abstact: - A disconnecto fo an SPD (Suge Potective Device) is equipment that disconnects a cicuit when the SPD fail in a shot cicuit mode. The disconnecto and the SPD ae connected in seies. A fuse o a cicuit beake is nomally used as a disconnecto. Howeve thee ae poblems with both methods. A fuse is not ecyclable once it goes out. Even a cicuit beake is esettable, a lightning suge cuent causes a switchgea of cicuit beake to open unnecessay. This malfunction spoils the ovevoltage potective function of the SPD which eliminates a lightning suge cuent into an electical appaatus. If the poblem which a switchgea of cicuit beake to open unnecessay can be solved, an electical appaatus can be potected by the SPD. This pape pesents seveal appoaches peventing cicuit beake type disconnectos fom the malfunction. Key-Wods :cicuit beake, disconnecto, suge potective device, shot cicuit mode, lightning suge 1 Intoduction This pape poposes a disconnecto that conducts a cuent geneated by lightning and that blocks a cuent fom a commecial powe supply. A disconnecto fo an SPD is equipment that disconnects a cicuit when the SPD may fail in a shot cicuit mode. The disconnecto and the SPD ae connected in seies. A fuse o a cicuit beake is nomally used as a disconnecto. Howeve thee ae poblems with both methods. A fuse is not ecyclable once it goes out. Even a cicuit beake is esettable, a lightning suge cuent causes a switchgea of cicuit beake to open unnecessay. Because electical contol cicuits of conventional cicuit beakes can not distinguish between a lightning suge cuent fom an altenative ovecuent. Anothe eason is a switchgea of the conventional cicuit beakes to open unnecessay accoding to the electomagnetic foce geneated by a lightning suge cuent. This malfunction caused by a lightning suge cuent spoils the ovevoltage potective function of the SPD which eliminates a lightning suge cuent into an electical appaatus. If the poblem which a switchgea of cicuit beakes to open unnecessay can be solved, even when lightning suge cuent flows though it, an electical appaatus can be potected by the SPD. We popose seveal appoaches peventing the switchgea malfunction using electical contol cicuit to be able to distinguish between a lightning suge cuent fom an altenative ovecuent as well as using loop foming switchgea stuctue. 2. Poblems on Disconnecto Fig. 1 is a configuation example of an ovevoltage potective device combining disconnectos and SPDs [1]- [11]. A disconnecto needs to be connected in seies to an SPD and be installed between an electic wie and an eath. Theefoe the disconnecto should conduct a cuent geneated by lightning and block a cuent fom a commecial powe supply. Howeve a lightning suge cuent causes a swichgea of cicuit beake to open unnecessay. Electical wie Disconnecto Disconnecto 1 2 SPD 1 Eath SPD 2 Electical Apaatus Main CB o FUSE Fig.1 Configuation example of ovevoltage potective device ISBN:

2 3. Impovements on Electical Contol Cicuits An object of the new appoaches is to povide a disconnecto that satisfies flowing a lightning suge cuent, blocking a cuent fom a commecial powe supply both in cases of eath fault and intephase shot cicuit. Because conventional cicuit beakes can not distinguish between a lightning suge cuent fom an altenative ovecuent. 3.1 Fist Idea Fig. 2 is a diagam showing a specific configuation example of the disconnecto 200. The cuent vecto sum detecting pat 150 is constituted by a diode 151 and esistos 152, 153, and 154. The bypass pat 160 is constituted by a tansisto 161 and a esisto Fig. 2 Specific configuation example of the disconnecto 200. Thee is no o little output voltage fom the ZCT 151 when thee is no lightning suge cuent, so the output voltage fom the cuent vecto sum detecting pat 150 is low. Theefoe, the tansisto 161 is OFF, and the cuent does not flow though the bypass pat 160. Thus, the output cuent fom the ectifying pat 110 geneated by the follow cuent is stoed in the chaging pat 120. When the lightning suge cuent flows, the output voltage of the cuent vecto sum detecting pat 150 becomes highe than the opeating voltage of the tansisto 161. The tansisto 161 then tuns on, and the cuent flows though the bypass pat 160. Theefoe, the output cuent fom the ectifying pat 110 geneated by the lightning suge cuent is hadly 134 stoed in the chaging pat 120. Thus, in the pesent appoach the value of Q (chage that can be stoed in the chaging pat by the lightning suge cuent) is vey small. The follow cuent can be blocked because the disconnecto 200 can set the capacitance value of the capacito 121 to the minimum capacitance that the tip coil 141 opeates the switchgea 142. Since the bypass pat 160 of the disconnecto 200 does not stoe the output cuent fom the CTs 101, 102, and 103 geneated by the lightning suge cuent in the chaging pat 120, thee is no fea that the lightning suge cuent opeates the switchgea 142. Fo example, a coil having a silicon steel sheet coe 30 mm in dimension and having 6000 tuns is used fo the ZCT. A coil having a silicon steel sheet coe 20 mm in dimension and having 3000 tuns is used fo the CT. The capacitance value of the capacito 121 is set to 17 μf, the capacitance value of the capacito 131 is set to 0.47 μf, the esistance value of the esisto 132 is set to 4.7 kω, the esistance value of the esisto 133 is set to 2.2 kω, and the esistance value of the esisto 162 is set to 6 kω. Such a disconnecto 200 does not opeate unde the lightning suge cuent of 50 ka and can block a 2 A (50Hz)o highe follow cuent. Shot cicuit beaking of about 10 ka (50Hz) is also possible. 3.2 Second Idea Fig. 3 shows a specific configuation example of the disconnecto 300. The delay pat 170 is constituted by a capacito 171, a esisto 172, a thyisto 173, a cuent limiting cicuit 174, and diodes 175 and 176. When the lighting suge is not geneated, thee is no output cuent fom the ectifying pat 110, and the chage of the capacito 171 is 0. Theefoe, the thyisto 173 is OFF, and the cuent fom the ectifying pat 110 does not flow though the chaging pat 120. When the lightning suge is geneated, the cuent fom the ectifying pat 110 is chaged to the capacito 171 though the cuent limiting cicuit 174. When the voltage of the capacito 171 exceeds a pedetemined value, the thyisto 173 is tuned on. The time fom the geneation of the lightning suge cuent to the tuning on of the thyisto 173 is a delay geneated by the delay pat 170. If the cuent value of the cuent limiting cicuit 174 and the capacitance value of the capacito 171 ae designed so that the delay time is seveal 100 μ seconds, the cuent fom the ectifying pat 110 by the lightning suge cuent is not chaged to the chaging pat 120. The esisto 172 is aanged to dischage the chage of the capacito 171 to etun the thyisto 173 to the initial OFF state when thee is no moe lightning suge cuent. The diodes 175 and 176 ae aanged to pevent the backflow. When the thyisto 173 is tuned on, the cuent fom the ectifying pat 110 is also chaged to the capacito 121 of the chaging pat 120. Howeve, the cuent is not chaged to the capacito 121 if thee is no follow cuent. Theefoe, the switching pat 140 is not diven. On the othe hand, the chage is stoed in the capacito 121 if thee is a follow ISBN:

3 cuent. When the chage stoed in the capacito 121 exceeds a pedetemined value, the tigge pat 130 dives the switching pat 140, and the electic wies ae disconnected. In the pesent appoach, the value of Q (chage that can be stoed in the chaging pat by the lighting suge cuent) is vey small. Theefoe, the capacitance C of the capacito 121 can also be made small. 300 The size of the vaious mateials used in the model of Fig. 4 is listed in Table 1. Moeove, wheneve the disconnecto opeates epeatedly, the contact suface of the silve 2 of a contact pat will be oundish. To estimate this effect, the contact suface of a switchgea having one point contact as shown in Fig. 5 was modeled. Table 1. Size of conventional model Mateial Y-axis beadth X-axis length Z-axis thickness Radius Fig.3 Specific configuation of the disconnecto 300. cicuit beake was modeled. Coppe Impovement of Switchgea 4.1 Poblems on Conventional Switchgea In conventional cicuit beake, when a lightning suge cuent flows, lage electomagnetic foce woks in the switchgea. In ode to investigate the chaacteistics of the electomagnetic foce in each conducto when the lightning suge cuent flows, as shown in Fig.4, the electode fom of Bass Silve Silve Coppe Bass One point contact Coppe (a) 3D model Silve2 Silve1 Bass Silve 2 Silve 1 (b) Coss section Fig.5 Conventional cicuit beake model ( One point contact model) Flat contact (a) 3 D model (b) Coss section Fig.4 Conventional cicuit beake model (Flat contact model) (1) Cuent density analysis The analyzed esults of cuent density, when both a 50Hz AC cuent and a lightning suge cuent flow into the conventional cicuit beake model, ae shown in Fig.6. When the cuent density of each conducto of the conventional cicuit beake model was seen, in the case of lightning suge cuent, compaed with AC ovecuent, the ISBN:

4 fequency component was high and it became clea that the influence of a skin effect appeas stongly. The esult of Fig. 7 shows that cuent is concentating at one point contact suface. When the vecto ingedient of cuent is decomposed as shown in Fig. 8(a), cuent flows in and flows out of one point contact point. As hoizontal components of the cuent vectos ae opposite diections, an electomagnetic foce woks to sepaate each othe as shown in Fig. 8(b) which means to make the switchge open unnecessay. (a) AC 50 ka (50Hz) A flowing in one point One point contact Total Cuent Cuent (decomposition ingedient) (b) Lightning Suge 50 ka Fig.6 Cuent density analyzed esults (Conventional cicuit beake model) Theefoe, since the lightning suge cuent makes difficult to pass though in the cental pat of each conducto and much cuent is flowing though the suface of a conducto. Fom this, it is expected that the powe geneated by lightning suge cuent is stonge than that of AC ovecuent. (a) Decomposition of cuent vectos I 1 I 2 I 1 I 2 F 12 F 21 F 12 F 21 B 2 B 1 B 2 B 1 (1) close togethe (2) sepaate each othe (b) Powe committed on paallel cuent Fig. 8. Electomagnetic foce to make the switchge open unnecessay Fig.7 Cuent vecto (Conventional cicuit beake one point contact model) The vecto of the cuent density when lightning suge cuent flows into a conventional cicuit model is shown in Fig. 7. (2) Electomagnetic foce analyzed esults The electomagnetic foce analyzed esult in the diection of the Z-axis committed to the conventional cicuit beake model when lightning suge cuent flows is shown in Fig.9. Hee, the Z-axis shows the top and bottom diection of the model. When the diection of powe which woks each mateial was seen fom the esult of Fig.9, the below powe woked to bass and silve 1, the above powe woked to silve 2 and coppe. And it became clea that the powe woking ISBN:

5 between conductos (bass, coppe) is bigge than the powe woking a contact pat (silve 1, silve 2). As these analyzed esults, it was poved that big powe in the diection of the Z-axis of a switchgea make a contact point comes open. The electomagnetic foce analyzed esult of the diection of the Z-axis committed to a loop fom model when lightning suge cuent flows is shown in Fig.11. As the electomagnetic foce to close togethe which woks between conductos (bass, coppe) is stonge than the electomagnetic foce to sepaate which woks in a contact pat (silve 1, silve 2). Fig.9 Electomagnetic foce analyzed esult of lightning suge cuent (Conventional cicuit beake one point contact model) Theefoe switchgea poblem to open unnecessay based on the electomagnetic foce in the diection of the Z-axis must be solved. 4.2 Impovement of Switchgea using Loop Fom Model As shown in Fig.10 we consideed the model which impoved bass foming loop. By making bass into loop fom, the cuent of the same diection flows between bass (top) and coppe. Although electomagnetic foce woks to sepaate bass (bottom) fom coppe simultaneously, electomagnetic foce woks to close togethe stonge because the distance of bass (top) and coppe is neae. Theefoe, it is thought that switchgea to open unnecessay can be solved. Bass Coppe Silve 1 Silve 2 Fig.11 Electomagnetic foce analyzed esult of lightning suge cuent (Loop fom model) Theefoe, the electomagnetic foce to close togethe woks between teminals if lightning suge cuent flows. In the case of lightning suge cuent, since stong powe is woking compaed with AC50kA (50Hz), it is expected that the point of contact of a switchgea does not intecept. It became clea that loop fom model is much bette than a conventional cicuit beake model. 5.Expeimental Test Results In ode to claify the validity of the poposed methods, we tested them as shown in Fig. 12. Fig.13 shows one example of lightning suge wavefom (class I, 10/350us) applicable fo diect lighting suge cuents. Based on the new appoaches, a disconnecto was developed fo an expeiment. Table 2 lists the test esults on opeation pefomance of the models unde the condition of lightning suge cuent. The switchgea of seveal conventional cicuit beakes could endue up to only 10~15kA (10/350μs). On the othe hand, the disconnecto using new appoaches could endue up to 40kA (10/350μs). We found that poposed model obtained good test esults. Fig.10 Loop fom model ISBN:

6 Fig. 12 Outlook of the expeiment. Fig. 14 Outlook of the poduct available on the maket Fig. 13 Lightning Suge wavefom used in expeiments. Disconnecto Table 2 Test Results Conventional cicuit beakes Poposed cicuit beake Expeimental esults 10~15kA ( 10/350μs) 40kA (10/350μs) 6.Poduct Specifications This disconnecto is available on the maket. The photogaph of the poduct is shown in Fig. 14. And main specifications of the poduct ae listed in Table 3. The disconnecto mentioned above is not affected by the voltage vaiation of the commecial powe supply due to the lightning suge supeposition o the like because the disconnecto is not supplied with an electical powe fom a commecial powe line. Also the voltage dop in the case of the lightning suge cuent is negligible because of using only cuent tansfomes without using electical elay. Voltage Applicable SPD Class Eath fault detection Shot cicuit cuent Table 3 Main Specifications AC100V,200V 50/60Hz ClassⅠSPD 40kA 2.5A o highe 7.5 ka 7.Conclutions This pape poposed a disconnecto that conducts a cuent geneated by lightning and that blocks a cuent fom a commecial powe supply. (1) The disconnecto using new appoaches could endue up to 40kA (10/350μs) in expeiments. (2) The 50Hz cuent of the commecial powe supply can be blocked both in cases of eath fault (2.5A o highe follow cuent) and intephase shot cicuit (7.5 ka ). (3) The disconnecto is not affected by the voltage vaiation of the commecial powe supply due to the lightning suge supeposition o the like because the disconnecto is not supplied with an electical powe fom a commecial powe line. Refeences [1] H. Kijima Ovevoltage potective device and method, Japanese patent No , 2006 [2]H. Kijima, Ovevoltage potective device and method, Koean patent No , 2008 [3] H. Kijima, Ovevoltage potective device and method, Austalian patent No , 2008 [4]H. Kijima, Ovevoltage potective device and method Chinese patent No.ZL X, 2010 [5] H. Kijima, Ovevoltage potective device and method, USA patent No , 2010 [6] H. Kijima, Ovevoltage potective device and method, EU patent application has been appoved, 2013 [7]H.Kijima, High voltage insulating tansfome, Japanese patent No , 2009 [8]M.Shibayama, H.Kijima, Disconnecto and ovevoltage potection device, USA patent No , 2011 [9]M.Shibayama, H. Kijima, Disconnecto and ovevoltage potection device, Japanese patent No , 2013 [10] H. Kijima, K.Yashio, Powe distibution boad with aesto, Japanese patent No , 2013 [11] K. Ochi, H. Kijima, Pulse shaping method, Japanese patent No , 2013 ISBN: