Cat Bucyrus Marion 151-M Dragline Electrical Instruction Manual - PDF DOWNLOAD

Technical Manual

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PART I- INTRODUCTION

The Marion ISI-M is a medium sized shovel or dragline using a direct current Ward-Leonard system with individual exciter control for powering all motions. The machines to be covered by these instructions use General Electric Co. "Amplidynes" as the individual exciters.

The motor generator set (M. G. set), mounted at the back of the machine, is driven by a3 phase alternating current induction motor. The incoming alternating current voltage is stepped down through transformers for operating the auxiliaries such as the air compressor, blowers, oil pumps and lights.

The generators driven by the induction motor are the exciter, the hoist generator, the swing generator, and the crowd generator. The exciter furnishes excitation for the Amplidyne control fields and the motor shunt fields. The generators furnish power for the main D. C. driving motor armature circuits. The hoist, swing and crowd Amplidyne units, which furnish the excitation for the generator separately excited fields, are mounted in the D. C. cabinet.

The hoist motor, a horizontal mill type, D. C. motor, furnishes power for the hoist drum and propel gears through a double gear reduction. The crowd motor, also a horizontal mill type, D. C. motor, is mounted on the boom and drives the crowd rack pinion through a gear train. The two swing motors are vertical mill type, D. C. motors, furnishing power for swinging through two sets of gears.

PART II - OPERATION

After the electrical adjustments have been made as described in Part III, the general sequence of operation is as follows:

A. Starting

Start the blower and oil pump motors by pressing the "Start" button mounted on the A. C. cabinet. Reset the undervoltage device by pressing in on the U -shaped plunger on the device. This device is mounted beside the Oil Circuit Breaker handle.

The M.G. set is started by pulling the Oil Circuit Breaker (O.C.B.) handle all the way out and then quickly pushing it in. The motor generator set may be stopped by lifting the trip lever beside the O. C. B. handle.

With the M. G. set running, the "Exciter Emergency-Start" button on the control station may be pressed, energizing the LE contactor. This contact or carries the power for the Amplidyne control fields, control contactors and magnet valves. When the "Stop" button is pressed, LE opens, removing excitation from the generators and setting the hoist, crowd and swing brakes.

When the operator leaves the controls or the machine is to be stopped for a short time, the "Stop" button should be pressed to set the brakes and deenergize the controllers. To energize the controllers again, the "Start" button is pressed.

B. Hoist Operation

1. The speed and direction of rotation of the hoist drum is controlled by oper.ating the right hand controller in front of the operator. Pulling back on the controller handle will raise the bucket and moving the handle forward will lower the bucket. There are five points or positions of the controller for hoisting, five for lowering and one for the neutral point. The speed of the motor is increased as the controller is moved point by point away from the neutral or center position.

Z. The hoist Amplidyne control field is energized, reversed and strengthened or weakened by the contacts in the hoist controller. Pulling the hoist controller to the first position back will energize the control field in one direction, while moving the hoist controller to the first position out will energize the field in the opposite direction.

Moving the hoist controller to each successive point in either direction will short out resistor HR18-HR19 on the second point, HR19HRZO on the third point, HRZO-HRZI on the fourth point and HRZlHRZZ on the fifth point. Each step thus increases the current in the Amplidyne control field by decreasing the resistance in series with the field.

The hoist controller also energizes the hoist motor field contactor, HMF. A ,rectifier in series with the HMF contactor coil prevents the HMF contactor from being energized in the lowering direction but allows the contactor to be energized in the hoisting direction. When propelling, an interlock on the propel brake magnetic switch shorts out the rectifier so that HMF can close in either direction.

The HMF contactor shorts out part of the resistance in series with the hoist motor shunt field and thus increases the field strength. The field is not strengthened for lowering so that a higher motor speed may be obtained.

3. The hoist motor is coupled to the hoist drum through the hoist clutch. (Note: The hoist clutch is sometimes referred to as the hoist ram.) This clutch is air engaged and spring released. The air pressure used to engage the clutch is controlled by a magnet operated valve which is open when the magnet is deenergized. Turning the hoist clutch selector switch to "Release" will energize the magnet valve, close the valve, and allow the spring to release the clutch. Turning the selector switch to "Engage" will deenergize the magnet valve and the air pressure will engage the clutch. When the Hoist Clutch selector switch is turned to "Release" the hoist brake will set, keeping the dipper from falling while propelling.

4. The hoist drum can be held from turning by setting the hoist brake. This brake is spring set, air released. The air pressure is controlled by means of a magnet operated valve which is closed when the magnet valve is deenergized.

The hoist brake magnet valve is energized through the Hoist Clutch selector switch and the Hoist Brake selector switch. When the Hoist Clutch selector switch is turned to "Release", the magnet valve will be deenergized and the brake will set. With the Hoist Clutch selector switch turned to "Enlage", the hoist brake may be controlled by the Hoist Brake Selector switch.

The hoist brake is used only to hold the drum while propelling or when the machine is stopped.

When the boom is raised too hilh, due to "jackinl" with the hoist or crowd motions, the Boom Limit Switch will open the LE CODtactor which will deenergize the controllers and set the brakes. The operator must then press the "Exciter Emergency-Start" pushbutton to release the brakes and energize the controllers.

C. SwinlOperation

1. The direction and speed of swiqinl is controlled by operatinl the foot pedals in front of the operator. Pushing on the right hand pedal will cause the machine to swinl to the right, and pushing on the left pedal will swinl the machine to the left. A spring is used to hold the pedals and controller in the neutral position.

There are five points of control in each direction. As the pedals are pushed down point by point, the speed will increase. When the machine is swinginl in one direction, to stop or reverse the rotation, allow the pedal to return to neutral and push on the opposite pedal. This operation is called "plugging". When the controller is in neutral, the machine may drift slowly. To stop the drift, it is only necessary to plug the swinl to a standstill.

z. The electrical operation of the swinl controller is the same as the operation of the hoist controller.

3. The machine can be held from swinging by settinl the swing brake. This brake is spring set, air released and may be released by turning the Swing Brake switch on the control station to the "Release" position. The swinl brake magnet valve will then be energized, the valve will open, and the air pressure will release the brake. By turning the selector switch to "Set", the magnet valve will be deenergized, the valve will close and the spring will set the brake.

The swinl brake is used only to hold the machine while propelling or when stopped.

D. Crowd Operation

1. The direction and speed of crowding is controlled by operating the left hand controller. Pulling back on the controller handle will pull the bucket in and pushing the handle out will move the bucket out.

Z. The electrical operation of the crowd controller is the same as the operation of the hoist controller.

3. The crowd machinery can be held from moving by setting the crowd brake. This brake is spring set. air released and may be released by turning the Crowd Brake switch on the control station to the "Release" position. The crowd brake magnet valve will then be energized. the valve will open. and the air pressure will release the brake. By turning the selector switch to "Set". the magnet valve will be deenergized. the valve will close and the spring will set the brake.

The crowd brake is used only to hold the crowd machinery while propelling or when stopped.

E. Propel and Steering Operation

1. Since the hoist motor is used for propelling as well as for driving the hoist drum. the hoist clutch must be released and the propel clutch engaged when propelling. The hoist clutch (or hoist ram) is controlled by a magnet operated valve. The valve is open when the magnet is deenergized. allowing air pressure to engage the clutch. The hoist clutch may be disengaged by turning the Hoist Clutch selector switch to "Release". This will energize the magnet valve. close the valve and a spring will disengage the hoist clutch. (With this selector switch in the "Release" position. the hoist brake will be set to hold the bucket while propelling.)

The propel clutch is controlled by the Propel Clutch selector switch. Turning the switch to "Engage" will energize the Propel Clutch magnet valve. opening the valve and allowing air to engage the clutch. Turning the switch to "Release" will deenergize the magnet valve. close the valve. and allow a spring to disengage the clutch.

Z. To prevent releasing the propel brake when the propel clutch is not engaged. a propel clutch limit switch is used. When the propel clutch is engaged. the limit switch contact will be closed and the Propel Brake contactor will be energized. This contactor will energize the propel brake oil pump motor through collector rings mounted between the upper and lower frames. The oil pump provides pressure to operate the cylinder and release the brake.

Turning the Propel Clutch selector switch to "Release" will deenergize the oil pump motor and allow a spring to set the propel brake.

3. Steering is controlled by means of the steering selector switch mounted on the control station. When the selector switch is turned to either "Right" or "Left". the corresponding lower frame solenoid valve is energized through the slip rings. These valves. when energized. allow oil to operate the steering clutches to steer the machine.

F. BOOIn Hoist Operation (If Used)

1. The bOOIn hoist druIn is also driven by the hoist Inotor so it is necessary to disengage the hoist clutch and engage the bOOIn hoist clutch when using the bOOIn hoist.

The hoist clutch is released by turning the Hoist Clutch selector switch to "Release" as Inentioned above.

The bOOIn hoist clutch is air engaged, spring released. Turning the BoOIn Hoist selector switch to "Engage" will energize the boom hoist Inagnet valve, opening the valve, and allowing the air pressure to engage the clutch. Turning the switch to "Release" will release the clutch.

z. With the bOOIn hoist clutch engaged and the hoist clutch disengaged, the bOOIn hoist druIn Inay be operated by the hoist controller.

G. Dipper Trip

The latch which holds the dipper door closed Inay be released by squeezing the thuInb switch on the crowd controller handle. This energizes the dipper trip Inotor, which drives the dipper trip cable druIn, opening the dipper door latch.

H. Auxiliary Controls

The air cOInpressor is used to provide air pressure for the operation of the various brakes and clutches. The cOInpressor is driven by a three phase Inotor which is controlled by a pressure switch. The pressure switch energizes the coil of the cOInpressor Inagnetic switch to autoInatically start the Inotor when the air pressure is low and to stop the Inotor when the pressure is built up. A switch is provided in the control station to be used for stopping the cOInpressor for servicing or when the Inachine is shut down.

Z.

The hoist, swing and crowd Inotors are forced-air cooled by Ineans of fans driven by three phase motors. A single or three phase motor is used to drive the swing gear case lubricating oil pumps. These motors are energized through a Inagnetic switch which is controlled by pushbuttons.

This three phase Inotor drives a fan used to exhaust air from the cab for cooling. The fan Inotor is controlled by a starting switch located in the A. C. cabinet.

1. Air COInpressor

Blower and Oil PUInp Motors

3. Cab Ventilating Fan Motor

The lights are controlled by switches mounted on the left wall of the cab. These switches are of the "no-fuze" type designed to open automatically under overload. To reset the switches after an overload, throw the handle to the "Off" position and then to the "On" position.

I. Dragline Operation

This machine can be changed to operate as a dragline by adding the necessary mechanical parts and making the required electrical changes.

For dragline operation, the swing motion is controlled by the left hand controller. (This controller is used for the crowd motion on a shovel.) The foot operated controller is removed on the dragline.

The hoist and drag clutches (or rams) are controlled by thumb operated switches mounted on the hoist and swing controllers.

The wiring changes necessary for converting to dragline operation are shown on the wiring diagram.

PART III - ELECTRICAL ADJU5TMENT5

A. Introduction

Before outlining the procedure to be followed in testing and adjusting the electrical apparatus on this machine, a brief description of the equipment will be helpful.

1. Ward-Leonard Control

The Ward-Leonard controlled electric shovel or dragline has a separate motor geared to each motion with each motor of the proper size for its particular duty. These motors are individually powered by specially designed excavator generators. The power and speed of each motion is controlled by varying the output of each generator through small master switches manipulated by the operator.

2. Generators

The generators used for Ward-Leonard control of the various motions of shovels or draglines are specially designed for this application. These generators have three main fields called the series field (denoted 51-52), the separately excited shunt field (labeled FI-F2) and the self excited shunt field (called F3-F4).

The series field, 51-52, is excited by the armature current and in conjunction with the Amplidyne current-limit field serves to limit the maximum current flowing from the generator. (Where Amplidyne

control is not used, the series field is much stronler.) The ser·iea field is cODDected differentially to the self and separate shunt fields. The self excited shunt field, F3-F4, is excited by the lenerator armature voltale. The self field is used on the swinl motion a.t all times and on the hoist motion when operated on Z5 or 50 cyc1efi.

The separately excited shunt field F I-FZ is excited by the Amplidyne armature voltale. As the Amplidyne voltale is reversed and strenlthened or weakened by the master switch, the lenerator separate field is varied, thus determininl the direction and strenlth of the lenerator output.

To make the necessary main lenerator settinls, the strenlths of the various Amplidyne fields are adjusted. The only main lenerator field that requires adjustment is the self field, when the self field is used.

The Amplidyne controlled Ward-Leonard excavator generator has a droopinl voltage characteristic shaped somewhat as shown by Curve B on pale 76. On Curve B, the no-load or open circuit voltage is shown at point D and the stall current at point E. Point F is the maximum or peak power point. The graph of power output in kilowatts is shown by Curve C. (Kilowatts are the product of voltage times current.)

In making the adjustments, the no-load voltale, stall current and peak power point are set to the desired values.

The amplidynes used to excite the excavator generators have fields specially designed for this purpose. These fields are the control field (denoted F3-F4), the current-limit field (denoted F5-F6), the anti-hunt field (denoted F7-F8) and the compensatinl field (denoted CI-CZ). The current-limit and anti-hunt fields are cODDected differentially to the control and compensatinl fields.

Since the armature voltale of the Amplidyne ia applied directly to the generator separate field, it follows that each of the Amplidyne fields can be used to control the generator output. These fields, then, are used to obtain the desired values of main generator noload voltale, stall current and peak power.

The Amplidyne control field F3-F4 is excited by the exciter volta Ie and is controlled by the master switch manipulated by the operator. This field current can be varied in both direction and strength, thus determining the output of the Amplidyne. The control field currezat is set to a predetermined maximum value for best operation of each motion.

The Amplidyne compensating field C I-CZ is excited by the Amplidyne armature current, which is also the lenerator field current. This

3. Amplidynes.

field is adjusted to give the proper compounding to the Amplidyne; that is, the compensatinl field determines what current the Amplidyne will furnish to the generator field, thus determining the generator no-load voltage. The field is adjusted by varying the resistance in parallel with the field. (There are taps on the compensatina field which could also be used for adjustment. The correct tap is determined at the factory and only the correct tap is connected to the terminal board on the Amplidyne. The other taps are taped up.) As the resistance is decreased, more current is shunted around the field, making the field weaker. The compensating field is adjusted for desired no-load voltage (with generators having separate field only). Where self fields are used on the main generators, they must also be used in adjusting the no-load voltage.

The Amplidyne current-limit field FS-F6 is excited by the voltage drop across the generator series and commutating fields and the motor commutating field of each motion, due to the armature current. This voltage is called the "current-limit voltage". The current-limit field is connected differentially to the control field and since its excitation depends upon the armature current, this field can be used to control the maximum current of the main generators. If the current-limit field were carrying current at all times, the generator voltage curve would be nearly a straight line from point D to point E on the curve, resulting in a very low peak power. To get a higher peak power, a special control using a "bias voltage" is employed. This bias voltage does not allow the current-limit field current to flow until the generator current exceeds about 40 to S01t of maximum.

The point at which the current limit field starts to carry current, called the "cut-off point", is shown as point G on the curves on page 76. Theoretically the generator voltage will then follow the dotted curve A as the current increases, but actually curve B will result. By using the bias voltage system of control, the peak power is adjusted to as high a value as the motor and generator limits of commutation will permit.

To explain the operation of the bias control system, figures 1 and 2 on pages 77 and 78 will be used. These figures show a typical current-limit circuit. For purposes of explanation, we will assume the following measurements have been taken on the circuit: (The method of taking the following readings is explained on later pages.)

Resistance of CRI-CR4 and CRI-CR5

Resistance of CR2 -CR3

Figure I shows the direction of current flow and the voltages measured when crowding "out" with 80 amperes (less than cut-off current) flowing. The circuit for crowding "in" would be the same except that the bias voltage would be across resistor CR I-CR4 instead of across resistor CRI-CR5 and the current and voltage directions would be reversed.

With these conditions, the following readings would be obtained:

Generator Current

Generator Voltage

Voltage from CRI to CR5 (crowd out)

Voltage from CR I to CR4 (crowd in)

Voltage from CGC2 to CMC 1

The voltages from CRI to CR5 and from CRI to CR4 are obtained from the main generator voltage through rectifiers. These voltages are called "bias voltages". The bias voltage will be across CRICR5 for one direction of rotation and across CRI-CR4 for the other direction of rotation. The voltage across CGC2 -CMC 1 is due to the generator current flowing through the generator series and commut3.ting fields and the motor commutating field. This voltage is called the "current-limit voltage".

As can be seen from the diagram, the bias voltage and current-limit voltage are connected so as to oppose each other. The voltage across the current-limit circuit (CRI6 to CAF6) will be the difference between the bias voltage and the current-limit voltage.

Under the above conditions, crowding out, the voltage across CRICR5 is greater than the voltage across CGC2 -CMC I, and current will try to flow through the current-limit field from CAF5 to CAF8. This current cannot flow, however, since it is blocked by the rectifier between CR5 and CRI6. Therefore, there will be no currentlimit field current.

The same will be true when crowding in except that the current will be blocked by the rectifier between CR4 and CRI6.

Figure 2 shows the direction of current flow and voltages measured when crowding "out" with 200 amperes (greater than cut-off current)

flowing. The conditions for crowding "in" would be the same except that the bias voltage would be across resistor'CR l-CR4 instead of resistor CR l-CR5 and the current and voltage directions would be reversed.

Under this condition, the following readings would be obtained:

Generator current Generator Voltage

Voltage from CR 1 to CR5

Voltage from CR 1 to CR4

Voltage from CGC2 to CMC1

Under these conditions, crowding out, the voltage across CGC2CMCl is greater than the voltage across CR1-CR5. Current will then flow through the current-limit field from CAF6 to CRl6 and through the rectifier between CR 16 and CR5. When crowding in, current-limit field current will flow in the opposite direction through the current-limit field and through the rectifier between CR4 and CRl6 instead of the rectifier between CRl6 and CR5.

From the above, it can be seen that the current-limit field carries current only when the generator current is greater than cut-off current. When the current-limit field carries current, the Arnplidyne voltage will be reduced, as can be seen from Curve H on page 76.

The Amplidyne voltage is nearly constant for low generator currents, as the curve indicates, but for currents greater than the cutoff current the Amplidyne voltage is reduced by the current-limit field. This decrease in Amplidyne voltage decreases the generator voltage.

The maximum or stall current from the main generator can thus be controlled by the current-limit field and the stall current can be set to the desired value by adjusting the current-limit field resistor.

The bias voltage must be set to equal the current-limit voltage at cut-off. To make this adjustment, the current-limit voltage is determined with the cut-off current flowing, as explained later, and the bias voltage set equal to this current-limit voltage.

By increasing the bias voltage, the cut-off current will be increased, thus increasing the peak power. Decreasing the bias voltage will give a resultant decrease in peak power. When the bias voltage

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