JPH03210092A - Pump overload operation preventing device - Google Patents
Pump overload operation preventing deviceInfo
- Publication number
- JPH03210092A JPH03210092A JP362490A JP362490A JPH03210092A JP H03210092 A JPH03210092 A JP H03210092A JP 362490 A JP362490 A JP 362490A JP 362490 A JP362490 A JP 362490A JP H03210092 A JPH03210092 A JP H03210092A
- Authority
- JP
- Japan
- Prior art keywords
- pump
- constant
- liquid supply
- liquid
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000007788 liquid Substances 0.000 claims abstract description 118
- 230000002265 prevention Effects 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 7
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 12
- 238000010586 diagram Methods 0.000 description 7
- 239000012530 fluid Substances 0.000 description 7
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
Landscapes
- Control Of Non-Positive-Displacement Pumps (AREA)
- Control Of Positive-Displacement Pumps (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はポンプ下流に給液調節弁を設は給液を行なう給
液装置に係り、特に、ポンプ過負荷運転を防止しかつポ
ンプ能力限界までの給液を可能とするポンプ過負荷運転
防止装置に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid supply device that supplies liquid by installing a liquid supply control valve downstream of a pump, and in particular, the present invention relates to a liquid supply device that supplies liquid by installing a liquid supply control valve downstream of a pump. The present invention relates to a pump overload operation prevention device that enables liquid supply up to
並列配置のポンプで給液を行なっている給液ポンプの過
負荷運転防止として、従来ポンプいずれかトリップ時、
残りのポンプが過負荷運転になることを防止するため給
水調節弁開度を一時一定開度、すなわち、ポンプ過負荷
となるポンプ通過流量以下の開度に保持しておく方式と
しており、保持の解除は、予備ポンプの起動９時限９手
動により行なう方式としており、特に、ポンプ運転状態
による過負荷運転防止回路は設けていなかった。Conventionally, when one of the pumps trips, to prevent overload operation of liquid supply pumps that supply liquid using pumps arranged in parallel.
In order to prevent the remaining pumps from operating overload, the water supply control valve opening is temporarily held at a constant opening, that is, at an opening below the pump flow rate that would cause pump overload. The release was carried out manually by starting the backup pump 9 times a day, and in particular, no overload operation prevention circuit was provided depending on the pump operating state.
なお、この種の給液制御装置に関するものに１例えば、
特開昭５５−６３３０３号公報が挙げられる。For example, there are some related to this type of liquid supply control device:
JP-A-55-63303 is mentioned.
上記従来技術は、給液制御信号にポンプ過負荷運転防止
については考慮されておらず、ポンプ過負荷運転の防止
はいずれかのポンプトリップ時のみであり、又、その手
法は給液調節弁の開度を一定時間先に決定した流量開度
に固定しておく方式であった。従って、調節弁の開度を
固定しておく時間設定にむずかしさがあり、又、トリッ
プしたポンプの慣性による給液能力、自動起動し昇速過
程にあるポンプの給液能力を充分に生かしていなかった
。The above conventional technology does not consider pump overload operation prevention in the liquid supply control signal, and prevents pump overload operation only when one of the pumps trips. It was a method in which the opening degree was fixed at a flow rate opening degree determined in advance for a certain period of time. Therefore, it is difficult to set the time to keep the opening of the control valve fixed, and it is also difficult to make full use of the liquid supply capacity due to the inertia of the tripped pump and the liquid supply capacity of the pump that has automatically started and is in the process of increasing speed. There wasn't.
第１図のごとく、各ポンプ出口に給液調節弁を設はポン
プ二台を常時起動し、−台を予備待機として給液を行な
っているシステムにおいて、−台のポンプがトリップし
た場合給液調節弁の動作は第２図の実線の弁動作となる
。この場合、弁開度固定を解除するタイミングが早いと
弁開度はポンプ過負荷流量以上の通液開度まで開しポン
プ過負荷となり、遅いと、給液の確保が遅くれる問題が
あった。これは継続運転しているポンプの状態信号によ
り調節弁開度を制御することで、弁開度を固定する必要
がなくなるため本発明で対策できる又、第３図に示すよ
うにトリップしたポンプ及び昇速過程にあるポンプの給
液は、継続運転中のポンプ出口側の圧損として働く。し
かし、現状の調節弁固定開度は継続運転中ポンプのみが
給液を行なっていてろ負荷とならない開度Ｂに設定され
ており、他のポンプが多少でも給液を行なっていればそ
の吐出圧力による出口圧損Ｅ分だけ平行移動し、Ｃの出
口側圧損カーブとなる。従って、運転継続しているポン
プの給液能力はまだ残っており給液調節弁は、さらに、
大開度のＤとすることが可能である。このＤの開度とす
ることは継続運転中、ポンプの状態信号により可能であ
る。As shown in Figure 1, in a system in which a liquid supply control valve is installed at the outlet of each pump, two pumps are always activated, and the - pump is on standby for liquid supply, if the - pump trips, the liquid is supplied. The operation of the control valve is as indicated by the solid line in FIG. In this case, if the timing of releasing the valve opening fixation is too early, the valve opening will open to a fluid passage opening that exceeds the pump overload flow rate, resulting in pump overload, and if it is too late, there is a problem in that securing fluid supply will be delayed. . This problem can be solved by the present invention by controlling the opening of the control valve based on the status signal of the continuously operating pump, which eliminates the need to fix the valve opening. The liquid supplied to the pump during the speed-up process acts as a pressure drop on the outlet side of the pump during continuous operation. However, the current fixed opening of the control valve is set to an opening B that does not cause a filter load if only the pump is supplying fluid during continuous operation, and if other pumps are supplying fluid even to some extent, the discharge pressure will be reduced. It moves in parallel by the amount of outlet pressure loss E due to , resulting in an outlet side pressure loss curve of C. Therefore, the liquid supply capacity of the pump that continues to operate still remains, and the liquid supply control valve further
It is possible to have a large opening D. It is possible to set the opening degree to D during continuous operation using the pump status signal.
本発明の目的はいかなる場合でもポンプの過負荷運転と
なることを防止しつつ、ポンプトリップ、予備機の起動
的にポンプの給液能力を最大に生かすポンプ過負荷運転
防止装置を提供することにある。An object of the present invention is to provide a pump overload operation prevention device that prevents overload operation of the pump under any circumstances and maximizes the liquid supply capacity of the pump in terms of pump trips and start-up of standby equipment. be.
上記目的を達成するために、給液ポンプ過負荷運転以下
の通過流量一定に保つ制御回路を設け、この通過流量要
求信号と、被給液側よりの給液要求信号を比較選択する
低値優先器を設け、この低値優先器により選択された信
号で給液調節弁を制御するようにしたものである。In order to achieve the above purpose, a control circuit is provided to keep the passing flow rate constant below the overload operation of the supply pump, and this passing flow rate request signal is compared with the supply request signal from the supplied liquid side to give priority to the low value. A signal selected by the low value priority device controls the liquid supply control valve.
ポンプの過負荷運転以下の通過流量一定に保つ制御回路
として、ポンプ吐出圧カ一定制御と、通過流量一定制御
、モータ駆動電流一定制御があげられる。Examples of control circuits that keep the flow rate constant under overload operation of the pump include constant pump discharge pressure control, constant flow rate control, and constant motor drive current control.
ポンプ下流の給液調節弁で給液を調節するシステムにお
いて、被給液側からの給液要求信号と、ポンプ過負荷運
転以下で通過流量を一定に保つ給水一定信号を比較し、
低値で給液調節弁を制御する。通常時、給液要求信号は
ポンプの給液能力以内であるが、ポンプが一台トリップ
した時、−時的に給液が減少し、残りのポンプに給液能
力以上の給液を要求する。この時、ポンプ過負荷運転以
下の通過流量一定制御信号が低値となり、給液をポンプ
能力以内の最大値一定に制御する。予備機の起動により
ポンプ給液が充分確保されると、給液要求信号が通過流
量一定制御信号以下となり、自動的に通常の給液制御と
なる。このように、常にポンプ能力以上の給液を行なわ
ないようにポンプ状態を監視していることになりポンプ
の過負荷運転は完全に防止される。In a system that adjusts the liquid supply with a liquid supply control valve downstream of the pump, the liquid supply request signal from the liquid receiving side is compared with the water supply constant signal that maintains the passing flow rate at a constant level under pump overload operation.
Control the liquid supply control valve at a low value. Normally, the liquid supply request signal is within the liquid supply capacity of the pump, but when one pump trips, the liquid supply decreases temporarily, and the remaining pumps are requested to supply liquid that exceeds the liquid supply capacity. . At this time, the constant flow rate control signal below the pump overload operation becomes a low value, and the liquid supply is controlled to a constant maximum value within the pump capacity. When the pump fluid supply is sufficiently secured by starting the standby machine, the fluid supply request signal becomes equal to or less than the constant flow rate control signal, and normal fluid supply control is automatically performed. In this way, the condition of the pump is constantly monitored to ensure that the liquid is not supplied in excess of the pump capacity, and overload operation of the pump is completely prevented.
ポンプ過負荷運転以下の通過流量一定制御として、ポン
プ吐出圧カ一定制御、ポンプ通過流量−定制御、ポンプ
駆動モータ電流一定制御がある。The constant flow rate control under pump overload operation includes constant pump discharge pressure control, constant pump flow rate control, and constant pump drive motor current control.
第４図にポンプ吐出圧力と流量、モータ駆動電流の関係
を示す。FIG. 4 shows the relationship between pump discharge pressure, flow rate, and motor drive current.
通常時、給液要求はポンプ過負荷運転以下のＡｌの給液
を要求し、給液調節弁開度はＡの圧損カーブを示す開度
となる。ポンプ過負荷点はＢｚの位置であり、ポンプ吐
出圧カ一定制御の設定値をｂｌに設定すると、吐出圧カ
一定制御はａｌの圧力をｂｌとするよう調節弁開度をさ
らに大開度とし、Ｂの圧損カーブを示す開度とするよう
に開要求を行なう。ポンプ通過流量一定制御の設定値を
ｂ２に設定すると、流量一定制御はａ２の流量をｂ２と
するように開要求を行なう。ポンプ駆動モータ電流一定
制御の設定電流をｂ８とするとａ３の電流をｂ３とする
ように開要求を行なう。Normally, the liquid supply request requests the liquid supply of Al below the pump overload operation, and the liquid supply control valve opening degree is an opening degree that shows the pressure drop curve A. The pump overload point is at the position Bz, and when the set value of the constant pump discharge pressure control is set to bl, the constant discharge pressure control sets the control valve opening to a larger opening so that the pressure of al becomes bl, An opening request is made so that the opening degree shows the pressure loss curve B. When the set value of the constant flow rate control through the pump is set to b2, the constant flow rate control requests opening so that the flow rate of a2 is set to b2. If the set current of the pump drive motor constant current control is set to b8, an opening request is made so that the current of a3 is set to b3.
このように通常時の給液要求信号は、ポンプ吐出圧カ一
定制御、ポンプ通過流量一定制御、ポンプ駆動モータ電
流一定制御よりも要求開度は小開度である。従って、通
常時は給液制御信号により調節弁は制御される。ポンプ
トリップによりポンプ給液が減少し、−時的に給液制御
信号により調節弁開度がＣとなった時、ポンプ吐出圧カ
一定制御はｂｌの圧力とするよう調節弁開度を小さくす
る要求信号を出力する。同様に通過流量一定制御もｂ２
とするよう調節弁開度を小さくする要求信号を出力する
。電流一定制御でもｂ３とするよう調節弁開度を小さく
するように要求信号を出力する。As described above, in the normal liquid supply request signal, the required opening degree is smaller than that in the constant pump discharge pressure control, the constant pump passage flow rate control, and the constant pump drive motor current control. Therefore, under normal conditions, the control valve is controlled by the liquid supply control signal. When the pump liquid supply decreases due to a pump trip and the control valve opening becomes C according to the liquid supply control signal, the pump discharge pressure constant control reduces the control valve opening so that the pressure is bl. Outputs a request signal. Similarly, constant flow rate control is also performed by b2.
A request signal is output to reduce the opening degree of the control valve so that the opening degree of the control valve is reduced. A request signal is output to reduce the opening degree of the control valve so that it becomes b3 even in constant current control.
従って、ポンプトリップにより給液要求が大となりポン
プ過負荷運転域以上に給液調節弁が開きポンプ吐出圧力
、ポンプ通過流量、ポンプ駆動モータ電流が過大となっ
た場合、ポンプ吐出圧カ一定制御、ポンプ通過流量一定
制御、ポンプ駆動モータ電流一定制御は給液調節弁開変
車要求を出力し本信号により給液調節弁が制御されポン
プは過負荷運転となることがない。ポンプトリップ後、
予備機が起動し給液が確保されはじめるとしだいに給液
要求信号は小となり過負荷運転域以下の給液要求となる
と低値優先回路により給液要求信号が選択され、給液要
求信号により給水調節弁が制御される。従って、ポンプ
能カー杯の給液を継続運転したポンプは行なうことにな
る。Therefore, if a pump trip causes a large liquid supply demand and the liquid supply control valve opens above the pump overload operating range, causing the pump discharge pressure, pump flow rate, and pump drive motor current to become excessive, the pump discharge pressure is controlled to be constant. The pump passage flow rate constant control and the pump drive motor current constant control output a request to open the liquid supply control valve, and this signal controls the liquid supply control valve so that the pump does not operate under overload. After pump trip,
As the standby machine starts up and the liquid supply begins to be secured, the liquid supply request signal gradually decreases, and when the liquid supply request falls below the overload operation range, the liquid supply request signal is selected by the low value priority circuit, and the liquid supply request signal is activated. The water supply control valve is controlled. Therefore, the pump that has been in continuous operation will continue to supply liquid to the pump capacity.
第５図にポンプ吐出圧カ一定制御、又は、通過流量一定
制御、ポンプ駆動モータ電流一定制御時にトリップ、又
は、自動起動昇速過程にあるポンプに多少の給液能力が
存在する場合の制御動作を示す。ポンプトリップ時、残
りのポンプの過負荷点はＢ１でありその時の給液調節弁
開度はＢである。他のポンプが給液を行なっていない場
合、各一定制御信号はＢの調節弁開度としＢ１の給液を
行なうように動作する。トリップポンプ、昇速過程にお
けるポンプが給液していた場合、そのポンプの吐出圧力
は継続運転しているポンプの出口側圧損として働く。従
って、給液調節弁の圧力損失カーブはＢ′となり継続運
転ポンプの給液は過負荷点Ｂ１以下のＢ２．どなる。こ
のため、各一定制御はＢ１まで給液量を増加させるため
、弁開度を大きくし、ＣとしＢｓの給液を行なう。以上
の動作により継続運転ポンプはΔＱだけ給液を増加させ
る。従って、給液もΔＱだけ増加する。Figure 5 shows the control operation when there is a trip during constant pump discharge pressure control, constant flow rate control, constant pump drive motor current control, or when there is some liquid supply capacity in the pump that is in the automatic startup speed increase process. shows. When the pump trips, the overload point of the remaining pumps is B1, and the opening degree of the liquid supply control valve at that time is B. When the other pumps are not supplying liquid, each constant control signal operates to set the control valve opening to B and supply liquid to B1. When a trip pump or a pump in the speed-up process is supplying liquid, the discharge pressure of that pump acts as the outlet side pressure loss of the continuously operating pump. Therefore, the pressure loss curve of the liquid supply control valve becomes B', and the liquid supply of the continuously operating pump is B2 below the overload point B1. bawl. Therefore, in each constant control, in order to increase the amount of liquid supplied to B1, the valve opening degree is increased and the liquid is supplied at C and Bs. By the above operation, the continuously operating pump increases the liquid supply by ΔQ. Therefore, the liquid supply also increases by ΔQ.
このようにポンプ吐出圧カ一定制御、ポンプ通過流量一
定制御、ポンプ駆動モータ電流一定制御の設定値をポン
プ過負荷運転域近傍一定にするポンプ下流側調節弁制御
信号のいずれか、又は、いずれかの組み合わせを給液要
求信号と比較し、その内の最低要求信号で給液調節弁を
制御することにより、ポンプ過負荷運転を防止し、ポン
プトリップ時に最大の給液を確保することが可能となる
。In this way, one or both of the pump downstream side control valve control signals keep the set values of the pump discharge pressure constant control, the pump passing flow rate constant control, and the pump drive motor current constant control constant near the pump overload operation region. The combination of Become.
以下、本発明の一実施例を説明する。第６図に本発明に
よる給液システムを示す。並列に設置された給液ポンプ
１をポンプ駆動モータ２で駆動しポンプ下流に設置した
給液調節弁３で給液流量を調節し給液を行なっている給
液システムにおいて、被給液側よりの給液要求信号５と
、ポンプ保護上の給液一定制御信号４を低値選択器７で
比較し、低値の信号を給液調節弁制御信号６として給液
調節弁３を制御し給液ポンプ通過流量、すなわち、ポン
プ負荷を調節する。ポンプ保護としての給液一定制御信
号の出力方式を第７図に示す。まず、流量一定制御とし
て、ポンプ通過流量を流量計８で検出しポンプ通過流量
をポンプ過負荷運転以下の流量設定値一定に制御する流
量一定制御演算器９を設け、給液一定制御信号４を出力
する方式がある。圧カ一定制御として、ポンプ吐出圧力
を圧力計１０で検出し、吐出圧力がポンプ過負荷運転以
下の圧力設定値一定に制御する圧カ一定制御演算器１１
を設け、給液一定制御信号４を出力する方式がある。電
流一定制御方式として給液ポンプ駆動モータ電流を電流
計１２で検出し、電流がポンプ過負荷運転以下の電流値
一定に制御する電流一定制御演算器１３を設け、給液一
定制御信号４を出力する方式がある。以上の流量一定制
御演算器９．圧カ一定制御演算器１１．電流一定制御演
算器１３よりの給液一定制御信号４のいずれか、または
、すべてを低値選択器７に入力し、給液要求信号５と比
較し、最低の信号により給液調節弁３を制御することに
よりポンプ過負荷運転を防止する。本実施例によれば、
第８図に示す給液調節弁動作となり、ポンプの過負荷運
転を防止しつつ、トリップしたポンプ、及び、起動昇速
過程にあるポンプが給液を多少でもしていればその吐出
圧力に応じ、さらに運転継続ポンプの給液調節弁の開度
を大開度として能カー杯の給液を確保することが可能と
なる。An embodiment of the present invention will be described below. FIG. 6 shows a liquid supply system according to the present invention. In a liquid supply system in which liquid supply pumps 1 installed in parallel are driven by a pump drive motor 2 and liquid is supplied by adjusting the liquid supply flow rate with a liquid supply control valve 3 installed downstream of the pump, The low value selector 7 compares the liquid supply request signal 5 with the liquid supply constant control signal 4 for pump protection, and uses the low value signal as the liquid supply control valve control signal 6 to control the liquid supply control valve 3 and supply liquid. Adjust the flow rate through the liquid pump, ie, the pump load. FIG. 7 shows the output method of the constant liquid supply control signal for pump protection. First, as a constant flow rate control, a constant flow rate control calculator 9 is installed to detect the flow rate passing through the pump with a flow meter 8 and control the flow rate through the pump to a constant flow rate set value below pump overload operation, and a constant flow rate control signal 4 is provided. There is a method to output. As constant pressure control, a constant pressure control calculator 11 detects the pump discharge pressure with a pressure gauge 10 and controls the discharge pressure to a constant pressure set value below the pump overload operation.
There is a method in which a constant liquid supply control signal 4 is output. As a constant current control method, a constant current control calculator 13 is provided which detects the liquid supply pump drive motor current with an ammeter 12 and controls the current to a constant current value below pump overload operation, and outputs a constant liquid supply control signal 4. There is a method to do this. The above constant flow rate control calculator 9. Constant pressure control calculator 11. Any or all of the liquid supply constant control signals 4 from the constant current control calculator 13 are inputted to the low value selector 7, and compared with the liquid supply request signal 5, and the liquid supply control valve 3 is activated based on the lowest signal. Control prevents pump overload operation. According to this embodiment,
The liquid supply control valve operates as shown in Figure 8, and while preventing overload operation of the pump, it responds to the discharge pressure if the tripped pump or the pump that is in the process of starting and speeding up is supplying liquid to some extent. Furthermore, it is possible to secure the liquid supply to the capacity cup by widening the opening degree of the liquid supply control valve of the continuous operation pump.
本発明によれば給液ポンプトリップ時、予備機の起動タ
イミングに関係なく、残りのポンプの過負荷運転投入を
防止することができ、ポンプ過負荷運転防止上効果があ
る。又、トリップしたポンプの慣性による給液及び昇速
過程にある。ポンプの給液能力に関係なく、ポンプ能カ
ー杯の給液を行なうことがら給液確保上も効果がある。According to the present invention, when the supply pump trips, it is possible to prevent the remaining pumps from starting overload operation regardless of the activation timing of the standby unit, which is effective in preventing pump overload operation. Also, the pump is in the process of supplying liquid and increasing speed due to the inertia of the tripped pump. Regardless of the liquid supply capacity of the pump, supplying liquid to the pump capacity cup is also effective in securing liquid supply.
第１図は本発明の一実施の給液システムの系統図、第２
図、第３図は従来方式の問題点の説明図、第４図、第５
図は本発明の原理を示す説明図、第６図は本発明による
給水制御の一実施例の系統図。
第７図は本発明による給液一定制御の一実施例の系統図
、第８図は本発明による給液調節弁の動作を示す説明図
である。
１・・・給液ポンプ、２・・・ポンプ駆動モータ、３・
・・給液調節弁、４・・・給液一定制御信号、５・・・
給液要求信号、６・・・給液調節弁制御信号、７・・・
低値選択器。
９・・・流量一定制御演算器、
１・・・圧カ一定制御演
第
図
ハ゛不＋！！明ＩＳよ３＃メ（の羅１糸↓り出口病Ｓた
禎
第４図
第
図Fig. 1 is a system diagram of a liquid supply system according to one embodiment of the present invention;
Figures 3 and 3 are explanatory diagrams of problems with the conventional method, Figures 4 and 5.
The figure is an explanatory diagram showing the principle of the present invention, and FIG. 6 is a system diagram of an embodiment of water supply control according to the present invention. FIG. 7 is a system diagram of an embodiment of constant liquid supply control according to the present invention, and FIG. 8 is an explanatory diagram showing the operation of the liquid supply control valve according to the present invention. 1...Liquid supply pump, 2...Pump drive motor, 3.
...Liquid supply control valve, 4...Liquid supply constant control signal, 5...
Liquid supply request signal, 6... Liquid supply control valve control signal, 7...
Low value selector. 9...Constant flow rate control calculation unit, 1...Constant pressure control calculation diagram ゛F+! ! Ming IS Yo 3
Claims (1)
求信号により給液調節を行なう給液装置において、ポン
プ給液能力値以内の給液一定制御信号と被供給側よりの
給液要求信号とを比較し、低値信号で前記調節弁を制御
することを特徴とするポンプ過負荷運転防止装置。1. In a liquid supply device in which a control valve installed on the pump outlet side adjusts the liquid supply based on a liquid supply request signal from the supplied side, a constant liquid supply control signal within the pump liquid supply capacity value and a liquid supply from the supplied side 1. A pump overload operation prevention device, characterized in that the control valve is controlled by a low value signal compared with a request signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP362490A JPH03210092A (en) | 1990-01-12 | 1990-01-12 | Pump overload operation preventing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP362490A JPH03210092A (en) | 1990-01-12 | 1990-01-12 | Pump overload operation preventing device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03210092A true JPH03210092A (en) | 1991-09-13 |
Family
ID=11562651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP362490A Pending JPH03210092A (en) | 1990-01-12 | 1990-01-12 | Pump overload operation preventing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03210092A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4956339A (en) * | 1987-09-21 | 1990-09-11 | Semiconductor Energy Laboratory Co., Ltd. | Method for manufacturing superconducting ceramics in a magnetic field |
| JP2012112257A (en) * | 2010-11-22 | 2012-06-14 | Kawamoto Pump Mfg Co Ltd | Water supply apparatus |
-
1990
- 1990-01-12 JP JP362490A patent/JPH03210092A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4956339A (en) * | 1987-09-21 | 1990-09-11 | Semiconductor Energy Laboratory Co., Ltd. | Method for manufacturing superconducting ceramics in a magnetic field |
| JP2012112257A (en) * | 2010-11-22 | 2012-06-14 | Kawamoto Pump Mfg Co Ltd | Water supply apparatus |
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