US3665277A - Motor and hoist control arrangement - Google Patents

Motor and hoist control arrangement Download PDF

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Publication number
US3665277A
US3665277A US62342A US3665277DA US3665277A US 3665277 A US3665277 A US 3665277A US 62342 A US62342 A US 62342A US 3665277D A US3665277D A US 3665277DA US 3665277 A US3665277 A US 3665277A
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Prior art keywords
motor
signal
power
power disconnect
disconnect
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Expired - Lifetime
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US62342A
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English (en)
Inventor
Edward Velazquez
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Textron Systems Corp
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AAI Corp
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
    • H02H7/0855—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load avoiding response to transient overloads, e.g. during starting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C15/00—Safety gear
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C2700/00—Cranes
    • B66C2700/08—Electrical assemblies or electrical control devices for cranes, winches, capstans or electrical hoists
    • B66C2700/084—Protection measures

Definitions

  • This invention relates to a motor control arrangement, and in particular to a control arrangement which is specifically useful and adapted to use as a hoist drive control for a hoist having an AC drive motor.
  • While motors are conventionally provided with built-in current overload responsive cut-off switches which operate after a given length of time on the basis of heat build-up or other abnormal operation indicators, such relatively slow acting motor overload protectors do not satisfy the requirements which must be met in order to prevent damage to the remaining hoist drive equipment, such as the clutch or clutches and the gears, as such remaining drive train equipment, as well as other portions of the hoist, may be very quickly damaged if the hoist is not relatively quickly stopped upon the attempt to lift or pull a grossly overloading weight or act against some other grossly overloading resistive force.
  • Still a further feature of the invention is the provision of such a motor control arrangement as applied to a practical hoist drive, in which a power disconnect means is operative during the operation of the hoist motor drive, but is rendered inoperative during the lowering of the hoist, when the motor and hoist are in different operating mode.
  • FIG. is a schematic electrical circuit of a hoist motor control arrangement according to the invention.
  • a motor and brake control arrangement is provided for a three phase AC motor M and a brake B, the motor being suitably mounted on a hoist and driving a take-up reel or drum, as through a suitable clutch and gear train drive of conventional construction (not shown).
  • the hoist may also be provided with a brake B which is required to be energized to release the brake during the operation of the motor M, as is conventional practice.
  • the motor M and brake B may be energized from any suitable source of three phase AC power, and it will also be appreciated that other AC power may be employed, including single phase power.
  • overload switches 0L1 and 0L2 may be provided for the motor, as generally indicated in the circuit diagram, although such are not required for operation of the present invention. Such are illustrated primarily as an optional feature in view of the normal provision of such switch or switches as a built-in operating feature of conventional commercial motors.
  • the present circuit does make arrangement for enabling the utilization of this optional additional overload disconnect arrangement.
  • the overload switches 01.1 and 0L2 being in series circuit relation with the motor M, have conventional latching contacts 0L1 and 0L2, respectively, which are arranged to effect disconnection of power to the motor M and the brake B in the event of overload sensing by these overload detectors 0L1 and 01.2.
  • Suchoverload detectors are normally relatively slow acting as heretofore noted, further additionally relatively fast acting overload protection is provided according to the invention.
  • the motor M and brake B are energized in either the up or down modes through the medium of push button switches UP and DN, respectively, the actuation of which push button switches is effective to energize power contactors U or D, respectively, which contactors are provided with normally open contacts U and D and which contacts U or D are thereby closed to supply power to the motor M and brake B as a direct function of closing the respective up or down switch UP or DN.
  • the motor M is driven in one direction by closing of the switch UP, and phase reversal is effected to the motor by closing of the switch DN, to thereby drive the motor in the opposite direction.
  • the brake B operates in the conventional fashion during either phase condition.
  • a power disconnect network is provided to prevent undue damage to the hoist or other drive mechanism upon the encountering of abruptly acting overload such as where the hoist is connected to a grossly excessive weight or to a fixed object, such as a bulkhead.
  • This power disconnect circuit includes a power disconnect relay and a relay operating switch in the form of a silicon controlled rectifier SCRl which is normally in the cut-off state under normal motor operating conditions, as well as prior to energization of the motor M.
  • An AC signal indicative of motor drive current is picked off as through the medium of a suitable transformer CT, the output of which transformer is connected through current limiting resistor R2 and diode CR1 to the gate or control electrode of the silicon controlled rectifier SCRl.
  • Variation of sensitivity of the rectifier SCRl to the current indicating signal from transformer CT is effected through the medium of variation of pick-off at the potentiometer R3, the pick-off arm of which is connected to the control electrode or gate of SCRl.
  • AC anode voltage is supplied to SCRl from an auxiliary transformer BT, through a line connection including overload contacts 0L1, 0L2, contactor D and its contact D and power disconnect relay K. It will thus be seen that in the quiescent condition of the circuit, anode current is supplied to the SCRI, and this current continues to be supplied until some portion of the supply line thereto is broken, as by opening of contact D as will be discussed later.
  • a power-disconnect-defeat network is provided in order to prevent actuation of the SCRl to conduction and power disconnect condition during a brief preselected period, commencing at motor start-up in the up mode and continuing for such brief predetermined period thereafter.
  • This powerdisconnect-defeat network takes the form of a bypass or shunting arrangement for the control signal from transformer CT and which is otherwise applied to the gate or control electrode of the SCRl.
  • the shunting or bypass arrangement includes a second silicon controlled rectifier switch SCR2 biased at its control electrode or gate to the conduction state prior to motor drive actuation by the closing of the up switch UP, as well as prior to actuation of the motor, and during its actuation by closing of the down switch DN.
  • This conduction state bias to the control electrode of the SCR2 is effected through a line connection from the secondary transformer BT, including overload switch contacts L1, 0L2, up contact U diode CR2, resistor R4, and discharge time delay resistantcapacitance circuit C2, R5, R6.
  • the capacitor C2 will be charged from the transformer BT through diode CR2, to a full charged value, thereby effecting an on condition bias on the gate of the SCR2.
  • power is applied to the drive motor M and brake B through contacts U1, and an AC signal is derived from transformer CT and applied through resistor R2 to the anode of SCR2, thereby effecting full signal bypass conduction of SCR2, diode CR1 (which is also preferably a silicon diode) being clamped in a cut-off condition by the prior conduction of SCR2.
  • contactor U remains open during the up mode of operation of the motor M, and is only rcclosed upon release of the switch UP and de-energization of the contactor U, at which time the capacitor C2 will again be charged to full value through the charge connection line from transformer ET.
  • the period of bypass or shunting condition of SCR2 may be selected to be of any desired relatively short (or long, if desired) value, such as for instance 200-300 milliseconds, which will be sufficiently long to prevent actuation of the power disconnect network, including SCRl and relay K, as a result of the normal motor surge current during motor startup.
  • this time delay period is primarily a function of the selected values of C2, R5 and R6.
  • the primary purpose of the capicator C1 is to prevent undesired actuation of the power disconnect switch SCRl upon the occurrence of normal very brief transient power spikes which conventionally occur in power lines, and which are normally of insignificant effect in causing any harm to the drive train of a hoist.
  • the SCRl Upon the encountering of a heavy resistive torque by the motor M, the current through the primary transformer CT will increase proportionately and the signal from the secondary transformer CT will likewise increase, and by setting the sensitivity of bias potentiometer R3 to a desired value, the SCRl will be triggered to conduction in response to a given current overload condition at the motor M. There will be some small delay in actuation of the switch SCRl, in view of the filtering energy absorbing action of the filter capacitor C1, this time delay being for instance of the order of 100-200 milliseconds after the occurrence of the overload indicating signal from transformer CT.
  • the relay K Upon conduction of SCRl, the relay K is energized, thereby moving double throw contacts K1 and K2 to their opposite throw conditions.
  • Contactor Kl may suitably be employed to energize an alarm such as a horn H, and contactor K2 serves to effect enclosing of a holding circuit through diode CR4 in parallel with SCRl, to thereby hold relay K in its energized condition, independent of subsequent cut-ofi' of SCRl, which cut-off of CR1 occurs as a result of actuation of relay K, deenergization of contactor U, and opening of power contacts U, in the power circuit to the motor M and transformer CT.
  • the coil of relay K may be suitably connected in parallel with a free-wheeling diode CR3, to maintain the relay K in actuated condition during both half cycles of the AC signal.
  • a capacitor C3 and resistor R7 are connected in series relation with the coil of relay K, through relay contact K2 which is normally in series closed ground return connection through capacitor C3 and resistor R7.
  • circuit may be modified to permit similar power disconnect control action for the motor M in either or both directions of motion of the motor.
  • Suitable upper and lower travel limit switches may be provided, such as indicated generally at ULS and DLS respectively, and which may be suitably connected in series with the respective power control contactors U and D, respectively, for upper and lower limit'de-energization of the motor M.
  • hoists are normally provided with a further auxiliary brake which is operational upon the stopping of the drive motor, and as such is conventional practice the provision of such auxiliary brake is not specifically shown or indicated on the circuit arrangement.
  • Such may, in fact, constitute only a clutch/brake arrangement of the mechanical variety and which is operative to prevent reverse or down motion of the motor and hoist except when the motor M is energized.
  • the motor M and brake B may be energized in either the up or down directions by pressing of push button switches UP or DN, respectively, thereby energizing contactors U and D respectively to effect closing of power contacts U, and D, respectively and the opening of normally closed contacts D and U respectively, the closing of either of the sets of power contacts U, or D, being effective to energize the motor M and brake B in each instance for effective motion of the motor in the requisite direction.
  • the current indicating signal from transformer CT is thus bypassed through SCR2 during the initial motor start-up time in the up motor direction, until bias voltage at the gate of SCR2 is below the cut-off value.
  • the diode CR1 is clamped below cut-off by the conduction of SCR2, thereby preventing the signal from transformer CT from effecting actuation of the power disconnect switch SCRl during such period.
  • the control arrangement Upon release of the down push button switch DN, the control arrangement will be restored to its full initial condition, with AC power applied to the anode of the SCRl, and with the capacitor C2 charged to conduction biasing condition for sCRZ, the SCRl being in the cut-off condition in view of the absence of an abnormal motor current flow indicating signal from the transformer CT.
  • the circuit is thus in readiness for the up actuation of the motor M and power disconnect control as heretofore described, or for further down mode operation of the motor M without power disconnect control, also as heretofore described.
  • a load-limiting motor control circuit arrangement comprising:
  • said signal-gating means comprising a current-shunting circuit
  • said power disconnect switching signal being a current which is a direct function of the quantum value of the AC current flow to said motor
  • said power disconnect means comprising:
  • a first normally cut-off electrical switch having a control electrode
  • said signal-gating means comprising:
  • a second electrical switch having a control electrode, an
  • motor current responsive means for detecting, and providing an electrical signal as a function of, current input to said motor
  • power disconnect means operating to disconnect electrical power to said motor in response to values of said signal indicating overload of said motor
  • signal bypass means effectively shunting said signal away from said power disconnect means during initial current surge as a function of motor start-up, and predetermined time interval time delay bypass disabling means effective to disable said bypass means after a selected predetermined time period from start-up.
  • motor current responsive means for detecting, and providing an electrical signal as a function of, current input to said motor
  • power disconnect means operative to disconnect electrical power to said motor in response to values of said signal indicating overload of said motor
  • signal bypass means effectively shunting said signal away from said power disconnect means during initial current surge as a function of motor start-up, and time delay means effective to disable said bypass means after a selected time period from start-up
  • said power disconnect means comprising a first controlled rectifier and a motor power control relay responsive to actuation and deactuation of said controlled rectifier, said relay having power control contacts in power control relation to said motor
  • said signal bypass means comprising a bypass switch in controlled signal-shunting relation to said first controlled rectifier, said time delay means being connected in shunt-controlling relation to said bypass switch.
  • a motor control circuit comprising a resistance-capacitance discharging circuit, charging means selectively connecting capacitor-charging power to said discharging circuit, and charge-disconnect means responsive to start-up actuation of said motor to effectively disconnect said discharging circuit from said charging means and thereby initiate a discharge period for said resistance-capacitance discharging circuit, the operative condition of said bypass switch being controlled by the effective charge of said resistancecapacitance discharging circuit.
  • a motor control circuit according to claim 5, and motion enabling means enabling rotation of said motor in one mode of motor operation beyond the control of said power disconnect means.
  • motor current responsive means for detecting, and providing an electrical signal as a function of, current input to said motor
  • said power disconnect means comprising a first controlled rectifier and a motor power control relay responsive to actuation and deactuation of said controlled rectifier
  • said relay having power control contacts in power control relation to said motor
  • said power disconnect means further comprising a protective filtering network normally connected in parallel relation to said first controlled rectifier,
  • relay-holding circuit means responsive to actuation of said first controlled rectifier to power disconnect state to thereby shunt both of said first controlled rectifier and said filtering network
  • said relay holding circuit means including a normally inactive rectifier in shunt-connectable relation to said first controlled rectifier and being operatively connected in shunting and similarly polarized rectification relation to said first controlled rectifier in response to said actuation of said controlled rectifier to power disconnect relation.
  • said relay holding circuit means comprising switch contacts operated as a function of actuation of said power disconnect relay
  • said switch contacts including a double throw contact arm normally connecting said filter network in operative protective filtering relation to said first controlled rectifier and movable in response to actuation of said relay to shunt said filter network and controlled rectifier and to connect said normally inactive rectifier into series holding relation with said relay.
  • said power disconnect means including a free-wheeling diode in parallel with an actuating coil of said relay to insure continued holding operation thereof during succeeding AC cycle reversals.
  • a lift-weight-restricting hoist arrangement comprising a hoist having a lift drive arrangement, said lift drive arrangement comprising: an AC drive motor in lift-driving relation to said hoist, to apply a lifting power to the hoist, means for sensing current flow to said motor and effecting a power disconnect signal as a function of the quantum value of said current flow, power disconnect means responsive to said power disconnect signal for disconnecting power to said motor, and signal control means operative during motor start-up to to prevent efiective application of said power disconnect signal to said power disconnect means for efiective operation of said power disconnect means during a selected period commencing with and terminating after start-up.
  • said signal gating means being operative to prevent effective operation of said current sensing means through prevention of actuation thereof during said period.
  • a load-limiting motor control circuit arrangement comprising:
  • said signal-gating means comprising a current-shunting circuit
  • said power disconnect switching signal being a current which is a direct function of the quantum value of the AC current flow to said motor
  • said power disconnect means comprising:
  • a first electrical switch having a control electrode and two controlled current-conducting electrodes controlled by said control electrode and being normally in one electrical-conducting condition
  • said signal-gating means comprising:
  • a second electrical switch having a control electrode, an
  • time-controlling means operative as a function of the passage of a selected time period after removal of said enabling signal at said control electrode to effect reduction of control bias to said second electrical switch control electrode below cut-off and to maintain said control bias in the below-cut-off condition during continued running of said motor thereafter,
  • a load-limiting motor control circuit arrangement comprising:
  • said signal-gating means comprising a currentshunting circuit
  • said power disconnect switching signal being a current which is a direct function of the quantum value of the AC current flow to said motor
  • said signal-gating means comprising:
  • an electrical switch having a control electrode, an anode and a cathode

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Control Of Ac Motors In General (AREA)
  • Protection Of Generators And Motors (AREA)
US62342A 1970-08-10 1970-08-10 Motor and hoist control arrangement Expired - Lifetime US3665277A (en)

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US6234270A 1970-08-10 1970-08-10

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DE (1) DE2139251A1 (enExample)
FR (1) FR2102163B1 (enExample)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3965401A (en) * 1974-05-31 1976-06-22 Canton Textile Mills, Inc. Textile card crush roll operating system and method
US4085594A (en) * 1977-02-14 1978-04-25 Suntech, Inc. Control system for cooling tower fans
US4119896A (en) * 1976-05-28 1978-10-10 The Alliance Manufacturing Company, Inc. Sequencing control circuit
US4478315A (en) * 1981-11-16 1984-10-23 Mitsubishi Denki Kabushiki Kaisha Apparatus for operating an AC power elevator
US6311801B1 (en) * 1999-01-25 2001-11-06 Hiroyuki Takagi Brake control apparatus with auxiliary power source means
US20030194920A1 (en) * 2000-12-21 2003-10-16 Etienne Foch Electrical energy distribution system and contactor for such a system
RU2280944C1 (ru) * 2005-03-03 2006-07-27 Открытое акционерное общество "Электропривод" Устройство торможения асинхронного двигателя
US20090255765A1 (en) * 2005-07-11 2009-10-15 Toshiba Elevator Kabushiki Kaisha Elevator speed governor, speed governing method and program

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011113286B4 (de) * 2011-09-14 2014-09-11 H. Stoll Gmbh & Co. Kg Flachstrickmaschine

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB438390A (en) * 1934-09-20 1935-11-15 Gen Electric Co Ltd Improvements in protective arrangements for electric motors

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3965401A (en) * 1974-05-31 1976-06-22 Canton Textile Mills, Inc. Textile card crush roll operating system and method
US4119896A (en) * 1976-05-28 1978-10-10 The Alliance Manufacturing Company, Inc. Sequencing control circuit
US4085594A (en) * 1977-02-14 1978-04-25 Suntech, Inc. Control system for cooling tower fans
US4478315A (en) * 1981-11-16 1984-10-23 Mitsubishi Denki Kabushiki Kaisha Apparatus for operating an AC power elevator
US6311801B1 (en) * 1999-01-25 2001-11-06 Hiroyuki Takagi Brake control apparatus with auxiliary power source means
US20030194920A1 (en) * 2000-12-21 2003-10-16 Etienne Foch Electrical energy distribution system and contactor for such a system
US6683771B2 (en) * 2000-12-21 2004-01-27 Airbus France Electrical energy distribution system and contactor for such a system
RU2280944C1 (ru) * 2005-03-03 2006-07-27 Открытое акционерное общество "Электропривод" Устройство торможения асинхронного двигателя
US20090255765A1 (en) * 2005-07-11 2009-10-15 Toshiba Elevator Kabushiki Kaisha Elevator speed governor, speed governing method and program
US7954604B2 (en) * 2005-07-11 2011-06-07 Toshiba Elevator Kabushiki Kaisha Elevator speed control device, elevator speed controlling method and elevator speed controlling program

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Publication number Publication date
FR2102163A1 (enExample) 1972-04-07
FR2102163B1 (enExample) 1976-07-09
DE2139251A1 (de) 1972-04-27

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