10 Atlas A15 Amplifier

7/29/2019 10 Atlas A15 Amplifier

1/10

MODEL A15 POWER AMP/SERVOCONTROLLER Revised May 24, 2005

DESCRIPTION

The A15 is an electronic controller developed for the 15R rotary servovalve. It provides closedloop position control of the valve. The package includes: A pulse width modulation amplifier witha full bridge MOSFET output section that can provide up to 20A current to the load. RVDTexcitation and demodulation circuitry for valve position feedback which employs a unique

ratiometric architecture for improved temperature stability and transducer interchangeability.Internal compensation for maximizing closed loop bandwidth. In addition, monitoring circuitry toalert the operator that an over travel, over temperature or over current condition exists in theservovalve. The A15 also has internal shutdown if an output short is detected. Load current anddemodulated RVDT output are available on the front panel through BNC connectors. Loadcurrent, RVDT demodulated output, and fault signals are available as differential outputs as well asremote power up through the monitor connector.

SPECIFICATIONS

MECHANICAL

Dimensions: W-10.75" x D-8" x H-3.75"Weight: 7.0 poundsCase: Dust tight aluminum enclosure with gold anodize finishMounting: mount on cold plate with four 1/4" screws on

7.5"x10.5" rectangular pattern

TEMPERATURE

Temperature, operating, case: -25 to +65CTemperature, storage: -40 to +85C

POWER REQUIRED

Input voltage: 20-40 volts DC (28 volts nominal), single supplyInput current: 1A (idle)

20A (with 15R servovalve full open at 160-Hz)Remote power up: 12-15 volts DC @ 25mA (for activation of

small internal relay whose contacts can be


2/10

ADJUSTMENTS

Offset Input Balance adjustment and RVDT demodulator null adjustmentsmay be accessed through a removable clear window.

FAULT DETECTION

Audible alarm as well as visible display for fault conditions:open temperature sensor, over temperature, overtravel, overcurrent;and internal power supply voltage indicators

INPUT/OUTPUT

Command signal: isolateddifferential--input,51 ohms input resistance (standard)

through MS3102R14S-2P connector,4 V or 80 mA for full valve opening typical

Output current: 20A peak (internal shutdown if >20A for .1 sec.)Output resistance: .25 ohmSwitching frequency: 42 kHz (typical)RVDT excitation frequency: 20 kHz (typical)

PERFORMANCE WITH 15R SERVOVALVE 20% OPENING:

Bandwidth: -3dB @500Hz (typical)90 degree lag frequency: 350 Hz (typical)Step response, rise time: 1 ms. rise time, 1.5 ms. at overshoot, 2.5 ms. to settleOvershoot: 10-20% (typical)

_________________

Note: Specifications are subject to change.

For pricing and availability contact:ATLAS FLUID CONTROLS CORPORATION, INC.9206 Emmott Rd.,Houston, TX 77040Voice: 713-937-7335 FAX: 713-937-7303


3/10

CONNECTIONS TO A-15 PWM AMPLIFIER

I. Input MS3102E-14S-2P (connects to vibrator controller servo drive)

A--not usedB--Input highC--not usedD--Input return

Amplifier has 51 ohm input resistance measured between pins B--DThe 51 ohm resistor is connected to an op amp configured in adifferential voltage mode, so it will work if B and D are swapped.

II. High voltage power MS3102E-14S-6P

A--to high voltage solenoid coil (lo side) (remote power enable)B--to battery groundC&D--to +28V from DC-to-DC converter E&F--to DC-to-DC converter return

*Using Analytic Systems model VTC605-12-24 DC to DC converter Using 70-111224-5 (White Rodgers) model solenoid for remotepower up of DC-to-DC converter. Recommend connecting solenoidthrough a return pressure switch so that the amplifier can only be acti-

vated when low pressure oil is available for motor cooling.

III. MOTOR connector MS3102E-14S-6S, Note: units SN 1 thru 9 used MS3120E14S-6P

A&B--PWM + output--to motor C&D--PWM - output--to motor E----to thermistor F----thermistor return

IV. RVDT connector (20kHz excitation) MS3102E-14S-2S, Note: units SN 1 thru 9 usedMS3102E-14S-2P

A-- +RVDT excitationB-- -RVDT excitation


4/10

C--Motor current+ (differential voltage proportional to current)D--Motor current-

E--Status+ **F--Status- **G--Remote power relay hi* (+15V from vibe electronics)H--Remote power relay lo* (GND from vibe electronics)J--N.C. (shield from vibe electronics)K--N.C. (-15v on SERCEL DSD)

* If the A15 internal relay is used in conjunction with a remote solenoid:to activate high voltage power supply requires that 15 volts be appliedto pin A, and B is tied to ground. The relay coil is 720 ohmsin series with a 180 ohm resistor for total a total resistance of 900 ohms.

** Status is a differential voltage output with the following levels:

Motor Current Motor Temperature Displacement Differential(High) (Hot or Open Thermistor) Over travel) Output Voltage (+/- 0.9 volts)

OK OK OK 17.0VOK OK Not OK 14.5VOK Not OK OK 12.1VOK Not OK Not OK 9.6V

Not OK OK OK 7.3VNot OK OK Not OK 4.9VNot OK Not OK OK 2.5VNot OK Not OK Not OK 0.40V

CHECKING THE RVDT ELECTRICAL OFFSET

The RVDT demodulation circuit comes from the factory with the offset potentiometer set for a zerooutput voltage as measured at the Valve Position BNC connector. If the user feels the need tocheck that the offset is properly adjusted please follow these steps:

1) With the unit powered off, disconnect the RVDT, Input, Monitor and Motor cables.2) Connect an oscilloscope or voltmeter to the Valve Position BNC.3) Using a jumper clip, short the RVDT connector pins C and D together. (These pins

ordinarily connect to the RVDT secondary winding output.)4) Connect the power cable and power up the unit.5) Ignore the open thermistor alarm light and sonalert alarm.


5/10

8) Remove the clear plastic bezel on the amplifier front panel. This will require a smallPhillips Head screwdriver.

9) Power the unit back up and monitor the Valve Position BNC voltage with C and D shorted.10) Turn the 10-turn blue trimpot labeled RVDT OFFSET ADJ. while continuing to monitor the Valve Position BNC voltage. Adjust the trimpot for zero output voltage at the BNCconnector.

11) If necessary proceed to the next section on Input Balance Adjustment.

INPUT BALANCE ADJUSTMENT

The following procedure assumes that the RVDT Offset has been properly adjusted as detailed inthe preceding section. The rotary valve needs to be connected to cooling oil. If the rotary valve isinstalled on a seismic vibrator, the vibrator engine needs to be running and the low pressure used tosupply cooling oil to the valve motor needs to be at its normal operating pressure. High-pressureoil is not required, so the vibrator should be pressured down. The amplifier needs to have the inputcable disconnected from the amplifier input connector. All other cables (power, motor and RVDT)need to be connected. The monitor cable need not be connected.

1) With no input connected to the amplifier, connect a voltmeter or oscilloscope to the ValvePosition BNC connector.

2) Turn on the amplifier power.3) The valve should go to its null position and the Valve Position BNC voltage should read

0.00 20 mV.4) If the Valve Position voltage is outside the prescribed range, remove the clear plastic bezel.5) While monitoring the Valve Position BNC voltage, use a small slotted screwdriver or

trimpot adjustment tool to turn the blue trimpot labeled INPUT BALANCE ADJ. untilthe voltage falls into the proper range.

IF FOR SOME REASON THE ELECTRICAL BALANCE ADJUSTMENTS LISTED ABOVEDO NOT FIX THE PROBLEM, IT MAY BE NECESSARY TO MAKE A MECHANICALADJUSTMENT ON THE ROTARY VALVE: POSSIBLY ADJUSTMENT OF THEMECHANICAL STOPS ON THE VALVE, AN ADJUSTMENT OF THE RVDT OR REQUIREA FACTORY REPAIR. PLEASE CONTACT ATLAS FLUID CONTROLS CORPORATION

FOR HELP IF THIS IS THE CASE.


6/10


7/10


8/10


9/10


10/10

10 Atlas A15 Amplifier

Documents

Transcript of 10 Atlas A15 Amplifier