JP3741649B2

JP3741649B2 - Power switching device

Info

Publication number: JP3741649B2
Application number: JP2002001764A
Authority: JP
Inventors: 正行加藤
Original assignee: デンセイ・ラムダ株式会社
Priority date: 2002-01-08
Filing date: 2002-01-08
Publication date: 2006-02-01
Anticipated expiration: 2022-01-08
Also published as: JP2003204635A

Description

【０００１】
【発明の属する技術分野】
本発明は、負荷装置に電力供給を行っている交流電源が断たれたとき、他の交流電源に切り換える電源切換装置に関する。
【０００２】
【従来の技術】
図３に、従来の電源切換装置の構成を示す。この電源切換装置３１は、商用電源３２と負荷装置３３とを導通させるための第１の電磁開閉器３４と、発電機３５と負荷装置３３とを導通させるための第２の電磁開閉器３６とを有している。そして、正常時すなわち商用電源３２の非停電時には、第１の電磁開閉器３４を閉じて、商用電源３２からの交流電力を負荷装置３３に供給し、商用電源３２の停電時には、第２の電磁開閉器３６を閉じて、発電機３５からの交流電力を負荷装置３３に供給することにより、商用電源３２の停電時にも負荷装置３３に電力を供給できるようにしている。
【０００３】
また、負荷装置３３は、自らを保護するために供給電力の異常低下を検知する機能を備えている。すなわち、負荷装置３３は、供給電力の異常低下を検知すると、緊急停止して破損や事故を防止したり、あるいは図示しない無停電電源装置（ＵＰＳ：Uninterruptible Power Supply）を作動させて電力供給の瞬断による停止を防止したりする機能を有している。
【０００４】
【発明が解決しようとする課題】
ところで、電源切換装置３１の電源切換動作の際、短い時間ではあるが、第１および第２の電磁開閉器３４，３６が両方とも開いた時間が生じる。
【０００５】
すなわち、図４に示すように、第１の電磁開閉器３４を閉から開に切り換え、第２の電磁開閉器３６を開から閉に切り換える電源切換動作の際には、第１の電磁開閉器３４が開いた時点Ｔ1と第２の電磁開閉器３６が閉じた時点Ｔ2との間にタイムラグΔＴ1（＝Ｔ2−Ｔ1）が生じる。
【０００６】
また、第２の電磁開閉器３６を閉から開に切り換え、第１の電磁開閉器３４を開から閉に切り換える接点切換動作の際には、第２の電磁開閉器３６が開いた時点Ｔ3と第１の電磁開閉器３４が閉じた時点Ｔ4との間にタイムラグΔＴ2（＝Ｔ4−Ｔ3）が生じる。
【０００７】
これらのとき、負荷装置３３には商用電源３２と発電機３５のどちらからも電力が供給されないため、本来であれば負荷装置３３の入力電圧Ｖ1はゼロになるはずであるが、実際には入力電圧Ｖ1がゼロに降下しない場合がある。このような場合として、負荷装置３３が回生動作をするもの、すなわち入力電圧Ｖ1が低下したときにその低下分を自装置内から戻す機能を有するものである場合や、負荷装置３３の入力側に設けられたコンデンサ３７やコイルに蓄積された電力の影響で入力電圧Ｖ1が維持される場合などがあげられる。
【０００８】
このような場合、負荷装置３３側からは、商用電源３２と発電機３５のどちらからも電力が供給されなくなったにもかかわらず、入力異常が検知されない。このため、電力供給源が無停電電源装置に切り換わらない。
【０００９】
また、上述した接点切換動作におけるタイムラグΔＴ1，ΔＴ2、すなわち商用電源３２および発電機３５からの電力供給が絶たれる時間（瞬断時間）が、入力異常を負荷装置３３が検出するのに要する時間Ｔ0よりも短い場合も、負荷装置３３側によって、商用電源３２および発電機３５からの電力供給の瞬断が検出されない。このため、電力供給源が無停電電源装置に切り換わらない。
【００１０】
そして、いずれの場合も、電源切換装置３１の電源切換動作が終了した時点で、負荷装置３３への電力供給源が、商用電源３２と発電機３５の一方から他方に単に切り換わることになる。
【００１１】
このとき、商用電源３２と発電機３５を切り換える前と後とで、負荷装置３３への入力電圧の位相が変わらなければ、負荷装置３３は電源の切り換えによって何ら支障を来すことなく運転し続けることができる。
【００１２】
しかし、商用電源３２と発電機３５とを互いに同期を取って運転するといったことは通常は行われないため、電源を切り換える前と後とで、負荷装置３３への入力電圧の位相が変化することになる。その結果、負荷装置３３は、装置内の交流位相との位相ずれが生じている電流、すなわち、急激な変化を伴う電流の流入により支障を来すことになる。特に、電源を切り換える前と後とでの負荷装置３３への入力電力の位相が互いに逆位相になった場合、短絡などの重大な事故が発生し、負荷装置３３のみならず電源側にも障害を及ぼすことがある。
【００１３】
本発明は、このような事情の下に創案されたものであり、電源切換動作時における電力供給の瞬断を負荷装置に確実に検知させて、負荷装置を保護することができる電源切換装置を提供することを目的とする。
【００１４】
【課題を解決するための手段】
上記課題を解決するために、本発明の電源切換装置は、供給電力の異常低下を検知する機能を内部または外部に備えた１つの負荷装置と複数の交流電源との間に設けられ、負荷装置への電力供給源を何れか１つの交流電源から他の何れかの交流電源に切り換える電源切換装置において、何れか１つの交流電源から負荷装置に電力を供給しているときには閉じられ、他の何れかの交流電源から負荷装置に電力を供給する際に開かれる第１の機械的スイッチ手段と、他の何れかの交流電源から負荷装置に電力を供給しているときには閉じられ、何れか１つの交流電源から負荷装置に電力を供給する際に開かれる第２の機械的スイッチ手段と、第１および第２の機械的スイッチ手段の一方を閉から開に切り換えると共に他方を開から閉に切り換える電源切換動作が生じたことを検知するための電源切換検知手段と、第１及び第２の機械的スイッチ手段と負荷装置との間に設けられた出力遮断手段と、電源切換動作が生じたことを電源切換検知手段により検知し、負荷装置への電力供給を、少なくとも、負荷装置が供給電力の異常低下を検出するのに要する時間の間、出力遮断手段により強制的に遮断する制御手段とを備えている。
【００１５】
このように構成された本発明の電源切換装置は、負荷装置に電力供給を行っている交流電源に異常が生じた時などにおいて、負荷装置への電力供給源を他の何れかの交流電源に切り換えるべく電源切換動作を行うとともに、負荷装置への電力供給を、負荷装置が供給電力の異常低下を検出するのに要する時間以上の間強制的に遮断する。
【００１６】
したがって、本発明の電源切換装置によれば、電源切換動作時における電力供給の瞬断を負荷装置に確実に検知させて、負荷装置を保護することができる。
【００１７】
本発明の電源切換装置において、制御手段は、電源切換動作が生じた時点からの経過時間を測定するためのタイマ回路と、このタイマ回路による測定時間が予め設定された時間になるまで負荷装置への電力供給を遮断するように出力遮断手段を駆動する駆動回路とを備えることが望ましい。
【００１８】
このような構成を採用すると、タイマ回路によって遮断時間が正確に制御され、負荷装置は供給電力の異常低下を確実に検出できることとなる。
【００１９】
また、他の発明の電源切換装置は、供給電力の異常低下を検知する機能を内部または外部に備えた１つの負荷装置と複数の交流電源との間に設けられ、負荷装置への電力供給源を何れか１つの交流電源から他の何れかの交流電源に切り換える電源切換装置において、何れか１つの交流電源から負荷装置に電力を供給しているときには閉じられ、他の何れかの交流電源から負荷装置に電力を供給する際に開かれる第１の機械的スイッチ手段と、他の何れかの交流電源から負荷装置に電力を供給しているときには閉じられ、何れか１つの交流電源から負荷装置に電力を供給する際に開かれる第２の機械的スイッチ手段と、第１および第２の機械的スイッチ手段の一方を閉から開に切り換えると共に他方を開から閉に切り換える電源切換動作が生じたことを検知するための電源切換検知手段と、第１及び第２の機械的スイッチ手段と負荷装置との間に設けられた出力遮断手段と、を備え、電源切換検知手段は、高周波発振器で駆動される一次側回路と、この一次側回路による誘導電力を第１および第２の機械的スイッチ手段にそれぞれ印加する二次側回路と、第１および第２の機械的スイッチ手段の開閉状態に応じて変化する一次側回路のインピーダンスの変化に基づいて、電源切換動作が生じたことを検知するための検知回路とを有し、その検知によって出力遮断手段を動作させている。
【００２０】
このように構成された本発明の電源切換装置は、負荷装置に電力供給を行っている交流電源に異常が生じた時などにおいて、負荷装置への電力供給源を他の何れかの交流電源に切り換えるべく電源切換動作を行うとともに、電源切換動作時における電力供給の瞬断を負荷装置に確実に検知させて、負荷装置を保護することができる。
【００２１】
また、検知回路は、第１および第２の機械的スイッチ手段の両方が共に開かれたときに一次側回路に接続された抵抗の両端から得られる検知電圧値と、予め設定された参照電圧値とを比較する比較回路を有していることが望ましい。
【００２２】
この発明では、一次側回路のインピーダンス変化を抵抗と比較回路からなる簡単な回路を設けることで検知でき、しかも、２つの機械的スイッチ手段が同時に開となった状態をこの回路によって瞬時にかつ確実に検知できることとなる。
【００２３】
【発明の実施の形態】
以下、本発明の好適な実施の形態を図面に基づいて説明する。図１は、本発明の実施の形態にかかる電源切換装置の構成を示す回路図である。
【００２４】
この実施の形態に示す電源切換装置１は、商用電源（交流電源）２に接続された入力端子３と、発電機（交流電源）４に接続された入力端子５と、負荷装置６に接続された出力端子７とを有している。負荷装置６側は、供給電力が異常低下したときに、これを自ら検知し、図示しない無停電電源装置から電力供給を受けるなどして停止その他の障害を防止する保護機能を有している。
【００２５】
電源切換装置１の内部には、第１の電磁開閉器８と、第２の電磁開閉器９と、電源切換検知回路１０と、出力遮断回路１１と、制御回路１２とが設けられている。
【００２６】
第１の電磁開閉器８は、商用電源２から負荷装置６に電力を供給しているときには閉じられ、発電機４から負荷装置６に電力を供給する際に開かれる第１の機械的スイッチ手段である。
【００２７】
第２の電磁開閉器９は、発電機４から負荷装置６に電力を供給しているときには閉じられ、商用電源２から負荷装置６に電力を供給する際に開かれる第２の機械的スイッチ手段である。
【００２８】
電源切換検知回路１０は、第１および第２の電磁開閉器８，９の一方を閉から開に切り換えると共に他方を開から閉に切り換える電源切換動作が生じたことを検知するための電源切換検知手段である。
【００２９】
この例では、電源切換検知回路１０は、発振回路となる高周波発振器１５で駆動される一次側回路１６と、この一次側回路１６による誘導電力を第１および第２の電磁開閉器８，９の主接点８ａ，９ａにそれぞれ印加する二次側回路１７，１８とからなる高周波トランス２４と、第１および第２の電磁開閉器８，９の開閉状態に応じて高周波発振器側から見たインピーダンスが変化して電流値が変化し、その結果、一次側回路１６（高周波発振器１５）に接続された抵抗２２の両端電圧が変化することに基づいて、電源切換動作が生じたことを検知するための比較回路（検知回路）１９とを備えている。
【００３０】
比較回路１９は、一次側回路１６に接続された抵抗２２の両端に生ずる検知電圧値Ｖsと予め定められた参照電圧値Ｖrとを比較し、検知電圧値Ｖsが参照電圧値Ｖr以下になったら検出信号Ｓｇを出力するように構成されている。参照電圧値Ｖrは、第１および第２の電磁開閉器８，９の両方が共に開かれたときに抵抗２２の両端から得られる検知電圧値Ｖs0と、第１及び第２の電磁開閉器８，９の一方が閉じているときの抵抗２２の両端から得られる検知電圧値ＶSLの中間値である検知電圧値ＶSMに設定されている。
【００３１】
一次側回路１６側には、上述したように、一次側回路１６のインピーダンスの変化によって変化する検知電圧値Ｖsを検出するための抵抗２２が、電源Ｖｃｃに関し、高周波発振器１５（一次側回路１６）と直列に設けられている。また、二次側回路１７，１８には、高周波の交流を通過させるが低周波（商用電源２程度のサイクル）の交流は通過させないようにするためと、それぞれの回路１７，１８に流れる電流の直流成分を遮断し高周波トランス２４の偏磁を防止するために、小容量のコンデンサ２０，２１が設けられている。
【００３２】
出力遮断回路１１は、第１及び第２の電磁開閉器８，９から負荷装置６への電力供給経路に設けられた出力遮断手段である。出力遮断回路１１は、一対のサイリスタ１１ａ，１１ｂが互いに逆並列に接続してなる構成となっている。
【００３３】
出力遮断回路１１の入力側には、コンデンサ２３が設けられている。このコンデンサ２３は、従来の電源切換装置３１と負荷装置３３との間に並列に設けられたコンデンサ３７と同種のものである。コンデンサ３７の代わりに直列にコイルが設けられる場合もある。
【００３４】
制御回路１２は、電源切換動作が生じたことを電源切換検知回路１０により検知し、負荷装置６への電力供給を、少なくとも、負荷装置６側が供給電力の異常低下を検出するのに要する時間Ｔ0の間、出力遮断回路１１により強制的に遮断する制御手段である。
【００３５】
この例では、制御回路１２は、電源切換動作が生じた時点からの経過時間を測定するためのタイマ回路１３と、このタイマ回路１３による測定時間が設定時間Ｔになるまで負荷装置６への電力供給を遮断するように出力遮断回路１１を駆動する駆動回路１４とを備えている。設定時間Ｔは、負荷装置６が供給電力の異常低下を検出するのに要する時間Ｔ0以上に設定されている。
【００３６】
次に、上記のように構成された電源切換装置１の動作について説明する。
【００３７】
図２の動作説明図に示すように、電源切換装置１は、正常時すなわち商用電源２の非停電時には、第１の電磁開閉器８を閉、第２の電磁開閉器９を開に保って、商用電源２から負荷装置６に交流電力を供給する。一方、非常時、すなわち商用電源２の停電時には、第１の電磁開閉器８を閉から開に切り換えるとともに、第２の電磁開閉器９を開から閉に切り換える電源切換動作を行って、負荷装置６への電力供給源を発電機４に切り換える。
【００３８】
そして、商用電源２が復旧したら、第２の電磁開閉器９を閉から開に切り換えるとともに、第１の電磁開閉器８を開から閉に切り換える電源切換動作を行って、負荷装置６への電力供給源を再び商用電源２に切り換える。これらの電源切換動作は、図示しない接点切換回路によって行われる。
【００３９】
電源切換動作の際、第１および第２の電磁開閉器８，９が両方とも開いた時間が生じる。図２において△Ｔ１，△Ｔ２で示す部分がこの時間に相当する。この時、一次側回路１６側の抵抗２２の両端から得られる検知電圧値Ｖsは、最小値Ｖs0になる。これは、両電磁開閉器８，９が開いていると、二次側回路１７，１８には電流が流れず、高周波発振器１５から一次側回路１６側を見た場合、インピーダンスが大きくなるため、抵抗２２の両端から得られる電圧としては小さくなるためである。なお、第１および第２の電磁開閉器８，９の一方が開き、他方が閉じた状態では、二次側回路に電圧が誘起され電流が流れる。この状態は、高周波発振器１５から見ると、一次側回路１６から二次側回路１７，１８のいずれか一方に電流が流れたこととなり、一次側回路１６のインピーダンスが小さくなったことを意味する。この結果、検知電圧値Ｖsは、参照電圧値Ｖrより大きくなる。
【００４０】
比較回路１９は、一次側回路１６に接続される抵抗２２の両端から得られる検知電圧値Ｖsと参照電圧値Ｖrとを比較し、検知電圧値Ｖsが参照電圧値Ｖr（＝ＶSM）以下になったら検知信号Ｓｇを出力する。これにより、第１および第２の電磁開閉器８，９が両方とも開いたこと、すなわち電源切換動作が生じたことが検知される。検知信号Ｓｇは、制御回路１２に入力される。
【００４１】
制御回路１２は、検出信号Ｓｇを受け取ると、タイマ回路１３によりその時点からの経過時間の測定を開始すると同時に、駆動回路１４により出力遮断回路１１のサイリスタ１１ａ，１１ｂを瞬時にオフする。すなわち、出力遮断回路１１は、負荷装置６への電力供給を電源切換動作が生じたら瞬時に遮断する。そして、当該経過時間が設定時間Ｔになったら、駆動回路１４により出力遮断回路１１のサイリスタ１１ａ，１１ｂをオンし、負荷装置６への電力供給を再開する。
【００４２】
負荷装置６は、電力供給の再開前に次のように動作する。すなわち、時間Ｔ0が経過した段階で、負荷装置６側は、供給電力の異常低下を検出し、図示しない無停電電源装置からの電力供給を受けると共に運転モードが変えられる。運転モードを変える代わりに、負荷装置６を停止させても良い。なお、この供給電力の異常低下検出は、無停電電源装置に行わせるのが好ましいが、負荷装置６自体にその検知機能を持たせるようにしても良い。
【００４３】
このように、この実施の形態の電源切換装置１は、負荷装置６に電力供給を行っている一方の交流電源に異常が生じたら、負荷装置６への電力供給源を他方の交流電源に切り換えるべく電源切換動作を行うとともに、負荷装置６への電力供給を瞬時に遮断する。そして、電源切換動作開始時点からの経過時間が設定時間Ｔ、すなわち負荷装置６側が供給電力の異常低下を検出するのに要する時間Ｔ0以上になるまでは、電源切換動作が終了しても、負荷装置６への電力供給を再開しない。
【００４４】
したがって、この実施の形態の電源切換装置１によれば、電源切換動作時における電力供給の瞬断を負荷装置６側に確実に検知させて、負荷装置６を保護することができる。
【００４５】
すなわち、入力電源の切換時に、切換前の位相と異なった位相が入力されても、その異なった位相の入力が開始される前までに、負荷装置６への電源供給を一旦完全に断ち、その後しばらくしてからその異なった位相の入力が開始されることとなるので、負荷装置６の運転モードを変えたり、停止させたりする余裕が生じ負荷装置６を保護することができる。
【００４６】
また、負荷装置６側の入力異常検出が遅い場合であっても、電源切換装置１によって高速にて切換を検出し、負荷装置６への電源供給を停止し、その電圧断時間を長くすることができるので、負荷装置６を無停電電源装置にて動作させることが可能となり、その無停電電源装置によって完全な退避が可能となる。
【００４７】
また、第１および第２の電磁開閉器８，９の開閉状態の変化に連動させて入力異常を検出しているため、切換時の瞬断を高速かつ正確に検出できる。すなわち、一次側回路１６に接続される抵抗２２から得られる検知電圧値Ｖsに基づいて、電源切換動作が生じたことを検知するようにしたので、第１および第２の電磁開閉器８，９の開閉動作に連動して、電源切換動作が生じたことを瞬時にかつ正確に検知でき、負荷装置６への電力供給を確実に遮断することができる。
【００４８】
なお、上記の実施の形態では、交流電源が２系統の場合、すなわち、商用電源２と発電機４がそれぞれ１つずつの場合を例にとり説明したが、交流電源が３系統以上の場合にも本発明が適用可能であることはいうまでもない。
【００４９】
たとえば、交流電源が３系統の場合、上記の実施の形態の構成に、更に１つの電磁開閉器とこれに接続されたさらに１つの二次側回路とを付け加えることにより対応可能である。交流電源が３系統以上の場合、３つ以上の電磁開閉器のうち、１回毎の電源切換動作に関わる２つの電磁開閉器の一方が第１の電磁開閉器、他方が第２の電磁開閉器となる。
【００５０】
また、上述の実施の形態では、第１の電磁開閉器８の主接点８ａ，８ａや、第２の電磁開閉器９の主接点９ａ，９ａに、二次側回路１７，１８を接続しているが、第１および第２の電磁開閉器８，９が主接点に加え、その動作に連動している補助接点を有している場合は、二次側回路１７，１８を第１および第２の電磁開閉器８，９の当該補助接点に接続してもよい。
【００５１】
また、機械的スイッチ手段としては、電磁開閉器８，９の代わりに、リレー等の他の機械的スイッチ手段を有する断続器を使用しても良い。また、制御回路１２としては、タイマ回路１３を設けずに、単に出力遮断回路１１を遮断させる駆動回路１４のみを有するようにしても良い。この場合、出力遮断回路１１の復帰は、負荷装置６側からの信号や手動にて行わせることができる。また、交流電源の異常時ではなく、必要に応じ手動にて負荷装置６への電力供給を切り換える場合等にも本発明を適用することができる。
【００５２】
【発明の効果】
以上説明したように、本発明の電源切換装置によれば、交流電源の電源切換動作を行う際に、負荷装置への電力供給を、負荷装置側が供給電力の異常低下を検出するのに要する時間以上の間、強制的に遮断するようにしている。また、他の発明の電源切換装置によれば、交流電源の電源切換動作を行う際に、機械的スイッチ手段に対して高周波電力を印加して電源切換動作が生じたか否かを検知し、その検知によって出力遮断手段を動作させている。このような構成のため、電源切換動作時における電力供給の瞬断を負荷装置側が確実に検知でき、負荷装置を保護することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態にかかる電源切換装置の構成を示す回路図である。
【図２】本発明の実施の形態にかかる電源切換装置の動作説明図である。
【図３】従来の電源切換装置の構成を示す回路図である。
【図４】従来の電源切換装置の動作説明図である。
【符号の説明】
１：電源切換装置
２：商用電源
４：発電機
６：負荷装置
８：第１の電磁開閉器（第１の機械的スイッチ手段）
９：第２の電磁開閉器（第２の機械的スイッチ手段）
１０：電源切換検知回路（電源切換検知手段）
１１：出力遮断回路（出力遮断手段）
１２：制御回路（制御手段）
１５：高周波発振器（発振回路）
１６：一次側回路
１７：二次側回路
１８：二次側回路
１９：比較回路
Ｖs：検知電圧値
Ｖr：参照電圧値[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply switching device that switches to another AC power supply when an AC power supply that supplies power to a load device is cut off.
[0002]
[Prior art]
FIG. 3 shows a configuration of a conventional power supply switching device. The power supply switching device 31 includes a first electromagnetic switch 34 for conducting the commercial power supply 32 and the load device 33, and a second electromagnetic switch 36 for conducting the generator 35 and the load device 33. have. When the power supply is normal, that is, when the commercial power source 32 is not powered down, the first electromagnetic switch 34 is closed to supply the AC power from the commercial power source 32 to the load device 33. By closing the switch 36 and supplying AC power from the generator 35 to the load device 33, it is possible to supply power to the load device 33 even when the commercial power supply 32 is out of power.
[0003]
In addition, the load device 33 has a function of detecting an abnormal decrease in supply power in order to protect itself. That is, when the load device 33 detects an abnormal drop in the supplied power, the load device 33 stops emergency to prevent damage or accidents, or operates an uninterruptible power supply (UPS: Uninterruptible Power Supply) (not shown). It has a function to prevent stoppage due to disconnection.
[0004]
[Problems to be solved by the invention]
By the way, when the power supply switching operation of the power supply switching device 31 is performed, a time when both the first and second electromagnetic switches 34 and 36 are opened is generated although it is a short time.
[0005]
That is, as shown in FIG. 4, the first electromagnetic switch 34 is switched from closed to open and the second electromagnetic switch 36 is switched from open to closed. A time lag ΔT1 (= T2−T1) occurs between the time T1 when the opening 34 is opened and the time T2 when the second electromagnetic switch 36 is closed.
[0006]
In the contact switching operation of switching the second electromagnetic switch 36 from closed to open and switching the first electromagnetic switch 34 from open to closed, the time T3 when the second electromagnetic switch 36 is opened A time lag ΔT2 (= T4−T3) occurs between the time T4 when the first electromagnetic switch 34 is closed.
[0007]
At these times, since the load device 33 is not supplied with power from either the commercial power supply 32 or the generator 35, the input voltage V 1 of the load device 33 should be zero originally, but in actuality the input The voltage V1 may not drop to zero. As such a case, when the load device 33 performs a regenerative operation, that is, when the input voltage V1 is lowered, the load device 33 has a function of returning the reduced amount from the own device, or on the input side of the load device 33. The case where the input voltage V1 is maintained by the influence of the electric power stored in the provided capacitor 37 or coil can be given.
[0008]
In such a case, no input abnormality is detected from the load device 33 side even though power is not supplied from either the commercial power supply 32 or the generator 35. For this reason, a power supply source does not switch to an uninterruptible power supply.
[0009]
Further, the time lags ΔT1 and ΔT2 in the contact switching operation described above, that is, the time required for the load device 33 to detect the input abnormality is the time T0 when the power supply from the commercial power supply 32 and the generator 35 is cut off (instantaneous interruption time). In the case where the power supply is shorter, the power supply from the commercial power supply 32 and the generator 35 is not detected by the load device 33 side. For this reason, a power supply source does not switch to an uninterruptible power supply.
[0010]
In either case, when the power source switching operation of the power source switching device 31 is completed, the power supply source to the load device 33 is simply switched from one of the commercial power source 32 and the generator 35 to the other.
[0011]
At this time, if the phase of the input voltage to the load device 33 does not change before and after the commercial power supply 32 and the generator 35 are switched, the load device 33 continues to operate without causing any trouble by switching the power supply. be able to.
[0012]
However, since the commercial power supply 32 and the generator 35 are not normally operated in synchronization with each other, the phase of the input voltage to the load device 33 changes before and after the power supply is switched. become. As a result, the load device 33 is hindered by an inflow of a current that is out of phase with the AC phase in the device, that is, a current that involves a sudden change. In particular, when the phases of input power to the load device 33 before and after switching the power supply are opposite to each other, a serious accident such as a short circuit occurs, and not only the load device 33 but also the power supply side has a failure. May affect.
[0013]
The present invention was devised under such circumstances, and a power supply switching device capable of protecting a load device by causing the load device to reliably detect an instantaneous interruption of power supply during a power supply switching operation. The purpose is to provide.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, a power supply switching device according to the present invention is provided between one load device having a function of detecting an abnormal drop in supply power inside or outside and a plurality of AC power supplies. In the power supply switching device that switches the power supply source to any one of the other AC power supplies, the power supply source is closed when power is supplied from any one AC power source to the load device, and any other A first mechanical switch means that is opened when power is supplied from the AC power source to the load device, and is closed when power is supplied to the load device from any other AC power source. The second mechanical switch means that is opened when power is supplied from the AC power source to the load device, and one of the first and second mechanical switch means is switched from closed to open and the other is switched from open to closed. A power source switching detection means for detecting that a source switching operation has occurred, an output cutoff means provided between the first and second mechanical switch means and the load device, and a power source switching operation have occurred. And a control means for forcibly shutting off the power supply to the load device by the output shut-off means for at least the time required for the load device to detect an abnormal drop in the supplied power. I have.
[0015]
The power supply switching device of the present invention configured as described above is configured such that when an abnormality occurs in the AC power supply that supplies power to the load device, the power supply source to the load device is changed to any other AC power supply. A power supply switching operation is performed for switching, and power supply to the load device is forcibly cut off for a time required for the load device to detect an abnormal decrease in supply power.
[0016]
Therefore, according to the power supply switching device of the present invention, it is possible to reliably detect the instantaneous interruption of power supply during the power supply switching operation and to protect the load device.
[0017]
In the power supply switching device of the present invention, the control means supplies the load circuit with a timer circuit for measuring the elapsed time from the time when the power supply switching operation has occurred, and until the time measured by the timer circuit reaches a preset time. And a drive circuit for driving the output shut-off means to cut off the power supply.
[0018]
When such a configuration is adopted, the shut-off time is accurately controlled by the timer circuit, and the load device can reliably detect an abnormal drop in the supplied power.
[0019]
According to another aspect of the present invention, a power supply switching device is provided between one load device having a function of detecting an abnormal drop in supply power inside or outside and a plurality of AC power supplies, and a power supply source to the load device Is switched from any one AC power source to any other AC power source and is closed when power is supplied from any one AC power source to the load device, and from any other AC power source First mechanical switch means that is opened when power is supplied to the load device, and is closed when power is supplied to the load device from any other AC power source, and the load device is supplied from any one AC power source. A second mechanical switch means that is opened when power is supplied to the power source, and a power source switching operation that switches one of the first and second mechanical switch means from closed to open and the other from open to closed. Power switching detection means for detecting this, and output shut-off means provided between the first and second mechanical switch means and the load device, and the power switching detection means is driven by a high frequency oscillator. Depending on the open / close state of the primary side circuit, the secondary side circuit for applying the induced power by the primary side circuit to the first and second mechanical switch means, respectively, and the first and second mechanical switch means And a detection circuit for detecting that the power supply switching operation has occurred based on the change in the impedance of the primary side circuit that changes, and the output cutoff means is operated by the detection.
[0020]
The power supply switching device of the present invention configured as described above is configured such that when an abnormality occurs in the AC power supply that supplies power to the load device, the power supply source to the load device is changed to any other AC power supply. In addition to performing a power supply switching operation for switching, the load device can be reliably detected by detecting an instantaneous interruption of power supply during the power supply switching operation.
[0021]
The detection circuit has a detection voltage value obtained from both ends of the resistor connected to the primary side circuit when both the first and second mechanical switch means are opened, and a preset reference voltage value. It is desirable to have a comparison circuit that compares.
[0022]
In the present invention, the impedance change of the primary circuit can be detected by providing a simple circuit comprising a resistor and a comparison circuit, and the state in which the two mechanical switch means are simultaneously opened can be instantaneously and reliably detected by this circuit. Will be detected.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration of a power supply switching apparatus according to an embodiment of the present invention.
[0024]
A power supply switching device 1 shown in this embodiment is connected to an input terminal 3 connected to a commercial power supply (AC power supply) 2, an input terminal 5 connected to a generator (AC power supply) 4, and a load device 6. Output terminal 7. The load device 6 has a protective function for detecting when the supply power is abnormally reduced and detecting power failure from an uninterruptible power supply (not shown) and preventing other failures.
[0025]
Inside the power switching device 1, a first electromagnetic switch 8, a second electromagnetic switch 9, a power switching detection circuit 10, an output cutoff circuit 11, and a control circuit 12 are provided.
[0026]
The first electromagnetic switch 8 is closed when supplying power from the commercial power source 2 to the load device 6 and is opened when supplying power from the generator 4 to the load device 6. It is.
[0027]
The second electromagnetic switch 9 is closed when power is being supplied from the generator 4 to the load device 6 and is opened when power is supplied from the commercial power source 2 to the load device 6. It is.
[0028]
The power supply switching detection circuit 10 detects the power supply switching detection for detecting the occurrence of the power supply switching operation for switching one of the first and second electromagnetic switches 8 and 9 from closed to open and switching the other from open to closed. Means.
[0029]
In this example, the power supply switching detection circuit 10 includes a primary side circuit 16 driven by a high-frequency oscillator 15 serving as an oscillation circuit, and electric power induced by the primary side circuit 16 of the first and second electromagnetic switches 8 and 9. The impedance seen from the high-frequency oscillator side according to the open / close state of the high-frequency transformer 24 including the secondary-side circuits 17 and 18 applied to the main contacts 8a and 9a and the first and second electromagnetic switches 8 and 9, respectively. For detecting the occurrence of the power supply switching operation based on the change in the voltage across the resistor 22 connected to the primary side circuit 16 (the high frequency oscillator 15). And a comparison circuit (detection circuit) 19.
[0030]
The comparison circuit 19 compares the detection voltage value Vs generated at both ends of the resistor 22 connected to the primary side circuit 16 with a predetermined reference voltage value Vr, and when the detection voltage value Vs becomes equal to or lower than the reference voltage value Vr. The detection signal Sg is output. The reference voltage value Vr includes the detected voltage value Vs0 obtained from both ends of the resistor 22 when both the first and second electromagnetic switches 8 and 9 are opened, and the first and second electromagnetic switches 8. , 9 is set to a detection voltage value VSM which is an intermediate value of the detection voltage value VSL obtained from both ends of the resistor 22 when one of the two terminals is closed.
[0031]
On the primary side circuit 16 side, as described above, the resistor 22 for detecting the detection voltage value Vs that changes due to the change in the impedance of the primary side circuit 16 is related to the power supply Vcc, and the high frequency oscillator 15 (primary side circuit 16). Are provided in series. The secondary circuits 17 and 18 allow high-frequency alternating current to pass but low-frequency alternating current (a cycle of about 2 commercial power supplies) does not pass. In order to block the DC component and prevent the high-frequency transformer 24 from being demagnetized, small-capacitance capacitors 20 and 21 are provided.
[0032]
The output cutoff circuit 11 is output cutoff means provided in the power supply path from the first and second electromagnetic switches 8 and 9 to the load device 6. The output cutoff circuit 11 has a configuration in which a pair of thyristors 11a and 11b are connected in antiparallel to each other.
[0033]
A capacitor 23 is provided on the input side of the output cutoff circuit 11. This capacitor 23 is the same type as the capacitor 37 provided in parallel between the conventional power supply switching device 31 and the load device 33. A coil may be provided in series instead of the capacitor 37.
[0034]
The control circuit 12 detects the occurrence of the power switching operation by the power switching detection circuit 10, and at least the time T0 required for the power supply to the load device 6 to be detected at least by the load device 6 side is detected. During this period, the output cutoff circuit 11 forcibly cuts off.
[0035]
In this example, the control circuit 12 includes a timer circuit 13 for measuring an elapsed time from the time when the power supply switching operation occurs, and power to the load device 6 until the measurement time by the timer circuit 13 reaches a set time T. And a drive circuit 14 for driving the output cutoff circuit 11 so as to cut off the supply. The set time T is set to be equal to or longer than the time T0 required for the load device 6 to detect an abnormal decrease in supply power.
[0036]
Next, the operation of the power supply switching device 1 configured as described above will be described.
[0037]
As shown in the operation explanatory diagram of FIG. 2, the power supply switching device 1 keeps the first electromagnetic switch 8 closed and the second electromagnetic switch 9 open during normal operation, that is, when there is no power failure of the commercial power supply 2. Then, AC power is supplied from the commercial power source 2 to the load device 6. On the other hand, during an emergency, that is, during a power failure of the commercial power supply 2, the first electromagnetic switch 8 is switched from closed to open, and the second electromagnetic switch 9 is switched from open to closed. The power supply source to 6 is switched to the generator 4.
[0038]
When the commercial power source 2 is restored, the second electromagnetic switch 9 is switched from closed to open, and the first electromagnetic switch 8 is switched from open to closed to perform power supply switching operation. Switch the supply source to the commercial power source 2 again. These power supply switching operations are performed by a contact switching circuit (not shown).
[0039]
During the power switching operation, a time occurs when both the first and second electromagnetic switches 8 and 9 are opened. In FIG. 2, portions indicated by ΔT1 and ΔT2 correspond to this time. At this time, the detected voltage value Vs obtained from both ends of the resistor 22 on the primary circuit 16 side becomes the minimum value Vs0. This is because when both electromagnetic switches 8 and 9 are open, no current flows through the secondary side circuits 17 and 18, and when the primary side circuit 16 side is viewed from the high frequency oscillator 15, the impedance increases. This is because the voltage obtained from both ends of the resistor 22 is small. In addition, when one of the first and second electromagnetic switches 8 and 9 is opened and the other is closed, a voltage is induced in the secondary circuit and a current flows. This state means that, when viewed from the high-frequency oscillator 15, a current flows from the primary side circuit 16 to one of the secondary side circuits 17 and 18, and the impedance of the primary side circuit 16 is reduced. As a result, the detection voltage value Vs becomes larger than the reference voltage value Vr.
[0040]
The comparison circuit 19 compares the detected voltage value Vs obtained from both ends of the resistor 22 connected to the primary side circuit 16 with the reference voltage value Vr, and the detected voltage value Vs becomes equal to or lower than the reference voltage value Vr (= VSM). Then, the detection signal Sg is output. As a result, it is detected that both the first and second electromagnetic switches 8 and 9 are open, that is, that a power supply switching operation has occurred. The detection signal Sg is input to the control circuit 12.
[0041]
When the control circuit 12 receives the detection signal Sg, the timer circuit 13 starts measuring the elapsed time from that time, and at the same time, the drive circuit 14 instantaneously turns off the thyristors 11a and 11b of the output cutoff circuit 11. That is, the output cut-off circuit 11 cuts off the power supply to the load device 6 instantaneously when the power supply switching operation occurs. When the elapsed time reaches the set time T, the drive circuit 14 turns on the thyristors 11a and 11b of the output cutoff circuit 11 and restarts the power supply to the load device 6.
[0042]
The load device 6 operates as follows before restarting the power supply. That is, when the time T0 has elapsed, the load device 6 side detects an abnormal drop in supply power, receives power supply from an uninterruptible power supply (not shown), and changes the operation mode. Instead of changing the operation mode, the load device 6 may be stopped. Although it is preferable that the uninterruptible power supply device detect the abnormality in the supply power, the load device 6 itself may have a detection function.
[0043]
As described above, the power supply switching device 1 of this embodiment switches the power supply source to the load device 6 to the other AC power supply when an abnormality occurs in one AC power supply that supplies power to the load device 6. Accordingly, the power supply switching operation is performed, and the power supply to the load device 6 is instantaneously interrupted. Even if the power switching operation ends, the elapsed time from the start of the power switching operation is equal to or longer than the set time T, that is, the time T0 required for the load device 6 to detect an abnormal decrease in supply power. The power supply to the device 6 is not resumed.
[0044]
Therefore, according to the power supply switching device 1 of this embodiment, the load device 6 can be protected by reliably detecting the instantaneous interruption of the power supply during the power supply switching operation on the load device 6 side.
[0045]
That is, even when a phase different from the phase before the switching is input at the time of switching the input power source, the power supply to the load device 6 is once completely cut off before the input of the different phase is started, and thereafter Since the input of the different phase is started after a while, there is a margin for changing or stopping the operation mode of the load device 6, and the load device 6 can be protected.
[0046]
Even when the input abnormality detection on the load device 6 side is slow, the power supply switching device 1 detects the switching at a high speed, stops the power supply to the load device 6, and extends the voltage interruption time. Therefore, the load device 6 can be operated by the uninterruptible power supply device, and the uninterruptible power supply device can be completely retracted.
[0047]
Moreover, since the input abnormality is detected in conjunction with the change in the open / close state of the first and second electromagnetic switches 8 and 9, the instantaneous interruption at the time of switching can be detected quickly and accurately. That is, since the power supply switching operation is detected based on the detection voltage value Vs obtained from the resistor 22 connected to the primary side circuit 16, the first and second electromagnetic switches 8, 9 are detected. In conjunction with the opening / closing operation, the power supply switching operation can be detected instantaneously and accurately, and the power supply to the load device 6 can be reliably shut off.
[0048]
In the above embodiment, the case where the AC power source is two systems, that is, the case where the commercial power source 2 and the generator 4 are one each has been described as an example, but the case where the AC power source is three systems or more is also described. Needless to say, the present invention is applicable.
[0049]
For example, in the case where there are three AC power sources, it is possible to cope with the configuration of the above-described embodiment by adding one more electromagnetic switch and one more secondary circuit connected thereto. When there are three or more AC power sources, one of the two electromagnetic switches involved in the power switching operation for each time is the first electromagnetic switch and the other is the second electromagnetic switch among the three or more electromagnetic switches. It becomes a vessel.
[0050]
In the above-described embodiment, the secondary side circuits 17 and 18 are connected to the main contacts 8 a and 8 a of the first electromagnetic switch 8 and the main contacts 9 a and 9 a of the second electromagnetic switch 9. However, if the first and second electromagnetic switches 8 and 9 have auxiliary contacts that are linked to the operation in addition to the main contacts, the secondary circuits 17 and 18 are connected to the first and second You may connect to the said auxiliary contact of 2 electromagnetic switches 8 and 9.
[0051]
As the mechanical switch means, an interrupter having other mechanical switch means such as a relay may be used instead of the electromagnetic switches 8 and 9. Further, the control circuit 12 may have only the drive circuit 14 that shuts off the output cutoff circuit 11 without providing the timer circuit 13. In this case, the output cutoff circuit 11 can be restored by a signal from the load device 6 or manually. Further, the present invention can be applied not only when the AC power supply is abnormal but also when the power supply to the load device 6 is manually switched as necessary.
[0052]
【The invention's effect】
As described above, according to the power supply switching device of the present invention, when performing the power supply switching operation of the AC power supply, the time required for the load device to detect the abnormal decrease in the supply power is supplied to the load device. Forcibly shuts off during the above. Further, according to the power supply switching device of another invention, when performing the power supply switching operation of the AC power supply, it is detected whether the power supply switching operation has occurred by applying high frequency power to the mechanical switch means, The output shut-off means is activated by detection. Due to such a configuration, the load device can reliably detect an instantaneous interruption of the power supply during the power switching operation, and the load device can be protected.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration of a power supply switching apparatus according to an embodiment of the present invention.
FIG. 2 is an operation explanatory diagram of the power supply switching device according to the embodiment of the present invention.
FIG. 3 is a circuit diagram showing a configuration of a conventional power supply switching device.
FIG. 4 is an operation explanatory diagram of a conventional power supply switching device.
[Explanation of symbols]
1: power supply switching device 2: commercial power supply 4: generator 6: load device 8: first electromagnetic switch (first mechanical switch means)
9: Second electromagnetic switch (second mechanical switch means)
10: Power switch detection circuit (power switch detection means)
11: Output cutoff circuit (output cutoff means)
12: Control circuit (control means)
15: High frequency oscillator (oscillation circuit)
16: Primary side circuit 17: Secondary side circuit 18: Secondary side circuit 19: Comparison circuit Vs: Detection voltage value Vr: Reference voltage value

Claims

Provided between one load device having an internal or external function for detecting an abnormal drop in supply power and a plurality of AC power supplies, and supplying power to the load device from any one AC power supply to another In the power supply switching device that switches to any AC power supply,
A first mechanical switch means that is closed when power is supplied to the load device from any one of the AC power supplies, and is opened when power is supplied to the load device from any other AC power supply. When,
Second mechanical switch means that is closed when power is supplied to the load device from any of the other AC power supplies, and is opened when power is supplied to the load device from any one of the AC power supplies. When,
Power supply switching detection means for detecting that a power supply switching operation for switching one of the first and second mechanical switch means from closed to open and switching the other from open to closed has occurred;
An output blocking means provided between the first and second mechanical switch means and the load device;
The power supply switching detection means detects that the power supply switching operation has occurred, and the power supply to the load device is output for at least the time required for the load device side to detect an abnormal decrease in supply power. And a control means for forcibly shutting off by the shutoff means.

The control means includes a timer circuit for measuring an elapsed time from the time when the power supply switching operation occurs, and interrupts power supply to the load device until a measurement time by the timer circuit reaches a preset time. The power supply switching device according to claim 1, further comprising a drive circuit that drives the output shut-off means.

Provided between one load device having an internal or external function for detecting an abnormal drop in supply power and a plurality of AC power supplies, and supplying power to the load device from any one AC power supply to another In the power supply switching device that switches to any AC power supply,
A first mechanical switch means that is closed when power is supplied to the load device from any one of the AC power supplies, and is opened when power is supplied to the load device from any other AC power supply. When,
Second mechanical switch means that is closed when power is supplied to the load device from any of the other AC power supplies, and is opened when power is supplied to the load device from any one of the AC power supplies. When,
Power supply switching detection means for detecting that a power supply switching operation for switching one of the first and second mechanical switch means from closed to open and switching the other from open to closed has occurred;
An output blocking means provided between the first and second mechanical switch means and the load device,
The power supply switching detection means includes a primary side circuit driven by a high frequency oscillator, a secondary side circuit for applying inductive power by the primary side circuit to the first and second mechanical switch means, and the first And a detection circuit for detecting that the power supply switching operation has occurred based on a change in impedance of the primary circuit that changes according to an open / close state of the second mechanical switch means,
A power supply switching device characterized in that the output shut-off means is operated by the detection.

The detection circuit includes a detection voltage value obtained from both ends of a resistor connected to the primary circuit when both the first and second mechanical switch means are opened, and a predetermined reference voltage. 4. The power supply switching device according to claim 3, further comprising a comparison circuit for comparing the values.