Woodward VariStroke-DX User manual

Product Manual 35132
(Revision -, 3/2020)
Original Instructions
VariStroke-DX
Duplex Hydraulic Servo Skid
Installation and Operation Manual
Released

General
Precautions
Read this entire manual and all other publications pertaining to the work to be
performed before installing, operating, or servicing this equipment.
Practice all plant and safety instructions and precautions.
Failure to follow instructions can cause personal injury and/or property damage.
Revisions
This publication may have been revised or updated since this copy was produced.
To verify that you have the latest revision, check manual 26455 , Customer
Publication Cross Reference and Revision Status & Distribution Restrictions, on
the publications page of the Woodward website:
http://www.woodward.com/
The latest version of most publications is available on the publications page. If
your publication is not there, please contact your customer service representative
to get the latest copy.
Proper Use
Any unauthorized modifications to or use of this equipment outside its specified
mechanical, electrical, or other operating limits may cause personal injury and/or
property damage, including damage to the equipment. Any such unauthorized
modifications: (i) constitute "misuse" and/or "negligence" within the meaning of
the product warranty thereby excluding warranty coverage for any resulting
damage, and (ii) invalidate product certifications or listings.
Translated
Publications
If the cover of this publication states "Translation of the Original Instructions"
please note:
The original source of this publication may have been updated since this
translation was made. Be sure to check manual 26455 , Customer Publication
Cross Reference and Revision Status & Distribution Restrictions, to verify whether
this translation is up to date. Out-of-date translations are marked with . Always
compare with the original for technical specifications and for proper and safe
installation and operation procedures.
Revisions— A bold, black line alongside the text identifies changes in this publication since the
last revision.
Woodward reserves the right to update any portion of this publication at any time. Information provided by Woodward is
believed to be correct and reliable. However, no responsibility is assumed by Woodward unless otherwise expressly
undertaken.
Manual 35132
Copyright © Woodward, Inc. 2019
All Rights Reserved
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Contents
W ARNINGS AND N OTICES ..............................................................................................................3
E LECTROSTATIC D ISCHARGE A WARENESS ....................................................................................4
R EGULATORY C OMPLIANCE ..........................................................................................................5
C HAPTER 1. G ENERAL I NFORMATION .............................................................................................7
System Description .......................................................................................................................................8
Design Characteristics..................................................................................................................................9
Construction................................................................................................................................................10
C HAPTER 2. S YSTEM S PECIFICATIONS .........................................................................................16
C HAPTER 3. I NSTALLATION .........................................................................................................19
Receiving Instructions.................................................................................................................................19
Mounting Instructions..................................................................................................................................20
Hydraulic Connections ................................................................................................................................21
Electrical Connections.................................................................................................................................21
Input Power.................................................................................................................................................26
Shielded Wiring...........................................................................................................................................29
Wiring..........................................................................................................................................................29
VS-DX Configuration and Calibration .........................................................................................................29
C HAPTER 4. I NITIAL O PERATION ..................................................................................................32
VS-DX performance....................................................................................................................................38
VSC-DX Unit Trapped Air Releasing Procedure.........................................................................................39
VSC-DX Unit Tuning ...................................................................................................................................39
C HAPTER 5. R EPAIR AND T ROUBLESHOOTING ..............................................................................40
General........................................................................................................................................................40
Troubleshooting ..........................................................................................................................................41
C HAPTER 6. P RODUCT S UPPORT AND S ERVICE O PTIONS .............................................................44
Product Support Options.............................................................................................................................44
Product Service Options .............................................................................................................................44
Returning Equipment for Repair .................................................................................................................45
Replacement Parts......................................................................................................................................46
Engineering Services..................................................................................................................................46
Contacting Woodward’s Support Organization...........................................................................................46
Technical Assistance ..................................................................................................................................47
C HAPTER 7. A SSET M ANAGEMENT AND R EFURBISHMENT S CHEDULING P ERIOD ...........................48
C HAPTER 8. L ONG -T ERM S TORAGE R EQUIREMENTS ....................................................................49
R EVISION H ISTORY .....................................................................................................................50
D ECLARATIONS ..........................................................................................................................51
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Illustrations and Tables
Figure 1-1. Basic VS-DX Application and Configuration...............................................................................9
Figure 1-2. VS-DX Main Components (Junction Box Version)...................................................................10
Figure 1-3. VariStroke-DX, Junction Box Version, front view.....................................................................11
Figure 1-4. VariStroke-DX, Junction Box Version, Top View......................................................................11
Figure 1-5. VariStroke-DX, Junction Box Version, Bottom View ................................................................12
Figure 1-6. VariStroke-DX, Junction Box Version, Back View....................................................................12
Figure 1-7. VariStroke-DX, Junction Box Version, Side View.....................................................................13
Figure 1-8. VariStroke-DX, Without Junction Box Version, Front View......................................................14
Figure 1-9. VariStroke-DX, Without Junction Box Version, Rear View.......................................................14
Figure 1-10. VariStroke-DX, Without Junction Box Version, Bottom View.................................................15
Figure 2-1. VariStroke-DX, Hydraulic Schematic........................................................................................18
Figure 3-1. VS-DX Lifting Bracket Locations ..............................................................................................20
Figure 3-2. VariStroke-DX, Junction Box Version, Main Terminal Box, Wiring Points Access ..................22
Figure 3-3. VariStroke-DX, Junction Box Version, Main Terminal Block Connections Chart.....................23
Figure 3-4. VariStroke-DX, Junction Box Version, Wiring Diagram............................................................24
Figure 3-5. VariStroke-DX, VariStroke-DX, Without Junction Box Version, Wiring Diagram .....................25
Figure 3-6. Cylinder Position Sensor Connection Scheme.........................................................................26
Figure 3-7. PE Ground Connection Localization and Details, Junction Box Version .................................28
Figure 3-8. PE / Chassis Ground Connection Localization and Details, Without Junction Box Version (On
Both VS).................................................................................................................................28
Figure 4-1. Isolation Valve Lever Positions.................................................................................................33
Figure 4-2. VS-DX Unit Components Topology..........................................................................................34
Figure 4-3. VS-DX Unit with Both Servos Control Port Paths Isolated.......................................................34
Figure 4-4. VS-DX unit VS-GI Unit “A” with Control Isolation Valves in Open Position..............................35
Figure 4-5. VS-DX Unit with All Isolation Valves in OPEN (Not Isolating) Position....................................36
Figure 4-6. VS-DX Unit to Unit Control User Demanded Switchover Action Typical Performance............38
Figure 4-7. VS-DX Unit to Unit Control Switchover Action Typical Performance (One Unit Shutdown) ....39
Table 1-1. Definitions and Abbreviations ......................................................................................................7
Table 1-2. Woodward Reference Literature..................................................................................................7
Table 2-1. Environmental............................................................................................................................16
Table 2-2. Physical......................................................................................................................................16
Table 2-3. Electrical Specifications.............................................................................................................16
Table 2-3. VS-DX without Junction Box Version (to Each VS Unit)............................................................17
Table 2-4. Cylinder Position Sensor Requirements....................................................................................17
Table 2-5. Hydraulic Specifications.............................................................................................................18
Table 3-1. Recommended Fuse Ratings or Circuit Breakers.....................................................................27
Table 5-1.List of available Replacement Kits..............................................................................................40
Table 5-2. Trouble Shooting Data...............................................................................................................42
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Warnings and Notices
Important Definitions
This is the safety alert symbol used to alert you to potential personal injury hazards. Obey all
safety messages that follow this symbol to avoid possible injury or death.
•DANGER - Indicates a hazardous situation, which if not avoided, will result in death or serious injury.
•WARNING - Indicates a hazardous situation, which if not avoided, could result in death or serious
injury.
•CAUTION - Indicates a hazardous situation, which if not avoided, could result in minor or moderate
injury.
•NOTICE - Indicates a hazard that could result in property damage only (including damage to the
control).
•IMPORTANT - Designates an operating tip or maintenance suggestion.
Overspeed /
Overtemperature /
Overpressure
The engine, turbine, or other type of prime mover should be
equipped with an overspeed shutdown device to protect against
runaway or damage to the prime mover with possible personal injury,
loss of life, or property damage.
The overspeed shutdown device must be totally independent of the
prime mover control system. An overtemperature or overpressure
shutdown device may also be needed for safety, as appropriate.
Personal Protective
Equipment
The products described in this publication may present risks t
hat
could lead to personal injury, loss of life, or property damage.
Always wear the appropriate personal protective equipment (PPE) for
the job at hand. Equipment that should be considered includes but is
not limited to:
•Eye Protection
•Hearing Protection
•Hard Hat
•Gloves
•Safety Boots
•Respirator
Always read the proper Material Safety Data Sheet (MSDS) for any
working fluid(s) and comply with recommended safety equipment.
Start-up
Be prepared to make an emergency shutdown when starting the
engine, turbine, or other type of prime mover, to protect against
runaway or overspeed with possible personal injury, loss of life, or
property damage.
Overspeed /
Overpressure
Never close the drain line when supply pressure is present on the
VS-GI unit, otherwise the control output pressure can increase
suddenly and cannot be controlled by the input setpoint. This could
cause the turbine to overspeed. The supply pressure isolation valve
and the control pressure isolation valve should always be closed
prior to closing the drain line.
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Never disconnect the redundancy linkage between
VS
-
GI
s when
BOTH units are powered.
Lockout/Tagout (LOTO)
Ensure that personnel
are fully trained on LOTO procedures prior
to attempting to replace or service VS-DX on a "live" running prime
mover. All safety protective systems (overspeed, over temperature,
overpressure, etc.), as well as personal protective equipment (PPE),
should be checked prior to beginning work to prevent personal
injury, loss of life, or property damage.
Electrostatic Discharge Awareness
Electrostatic
Precautions
Electronic controls contain static
-
sensitive parts. Observe the
following precautions to prevent damage to these parts:
•Discharge body static before handling the control (with power to
the control turned off, contact a grounded surface and maintain
contact while handling the control).
•Avoid all plastic, vinyl, and Styrofoam (except antistatic
versions) around printed circuit boards.
•Do not touch the components or conductors on a printed circuit
board with your hands or with conductive devices.
To prevent damage to electronic components caused by improper
handling, read and observe the precautions in Woodward manual
82715 , Guide for Handling and Protection of Electronic Controls,
Printed Circuit Boards, and Modules.
Follow these precautions when working with or near the control.
1. Avoid the build-up of static electricity on your body by not wearing clothing made of synthetic
materials. Wear cotton or cotton-blend materials as much as possible because these do not store
static electric charges as much as synthetics.
2. Do not remove the printed circuit board (PCB) from the control cabinet unless absolutely necessary.
If you must remove the PCB from the control cabinet, follow these precautions:
•Do not touch any part of the PCB except the edges.
•Do not touch the electrical conductors, the connectors, or the components with conductive
devices or with your hands.
•When replacing a PCB, keep the new PCB in the plastic antistatic protective bag it comes in
until you are ready to install it. Immediately after removing the old PCB from the control cabinet,
place it in the antistatic protective bag.
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Regulatory Compliance
European Compliance for CE Marking: PENDING
Other I
nternational Compliance:
-
IECEX:
PENDING
North American
Compliance:
These listings are limited only to those units bearing the appropriate marking. Review the Compliance
Code table for more information.
CSA:
Certified for Class I, Div. 2 Groups A, B, C, D T4. For Use in Canada
and the United States. Certificate 2669905.
Special Conditions for Safe Use
Wiring must be in accordance with North American, European, or other International wiring methods as
applicable, and in accordance with the authority having jurisdiction.
For Zone 1 or Division 1: Conduit seals must be installed within 18 inches (457 mm) of the conduit entry
when used in zone 1 / Division 1 hazardous locations.
Field wiring must be suitable for at least 85 °C and 10 °C above the maximum fluid and ambient
temperatures.
The VS-DX Skid Certified for Zone 2 version must be used in an ambient temperature range from
-30 to +85°C (-22 to + 185⁰F).
Maximum hydraulic fluid temperature shall not exceed 70°C (158⁰F).
Connect external safety ground terminal to earth ground.
Compliance with the Machinery Directive 2006/42/EC noise measurement and mitigation requirements is
the responsibility of the manufacturer of the machinery into which this product is incorporated.
Under certain extreme circumstances, the non-metallic parts incorporated in the enclosure of this
equipment may generate an ignition-capable level of electrostatic charge. Therefore, do not install the
equipment in a location where the external conditions are conducive to the build-up of electrostatic charge
on such surfaces. In addition, only clean the equipment with a damp cloth.
Transient protection for the VariStroke is to be provided externally by the end user. The transient
protection device is to be set at a level not exceeding 140% of the peak rated voltage.
The installation of the VariStroke shall only be within a Pollution Degree 2 environment as defined in IEC
60664-1.
Explosion Hazard
—
Do not connect or disconnect while the circuit is
live unless the area is known to be non-hazardous.
Substitution of components may impair suitability for Class I,
Division 2 or Zone 2 applications.
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Risque d’explosion
—
Ne pas raccorder ni débrancher tant
que l’installation est sous tension, sauf en cas l’ambiance
est décidément non dangereuse.
La substitution de composants peut rendre ce matériel
inacceptable pour les emplacements de Classe I,
applications Division 2 ou Zone 2.
Safety Symbols
Direct Current
Alternating Current
Both Alternating and Direct Current
Caution, risk of electrical shock
Caution, refer to accompanying documents
Protective earth terminal
Frame or chassis terminal
!
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Chapter 1.
General Information
Table 1-1. Definitions and Abbreviations
VS
-
DX:
VariStroke-DX Duplex Hydraulic Servo Skid
VS
-
GI:
VariStroke-GI Servo
DCS:
Distributed Control System
In Control:
The unit actually controlling the position of the actuation system
Not In Control:
The unit acting as the backup to the In Control unit
Master / Slave:
The unit designated as the Master has yielded control to the other unit (Slave) by
link between the two VS-GI’s. The Unit designated as the Master will take control
during VS-DX startup.
CMRR
:
Common Mode Rejection Ratio
VHPC
:
VariStroke Hydraulic Power Cylinder
Table 1-2. Woodward Reference Literature
Manual
25071
:
Oils for Hydraulic Controls
Manual 25075:
Commercial Preservation Packaging
for Storage of Mechanical-Hydraulic Controls
Manual
2
6455:
Woodward Energy Segment Customer Publications: Cross-Reference by
Application Revision Status & Distribution Restrictions
Manual
35119
:
VS-I G1 VariStroke-I (VS-I)
Electro-hydraulic Actuator
Manual
35133:
VS-DX VariStroke-DX
Duplex Hydraulic Servo Skid, VS-I Servo Unit replacement procedure
Manual 35148:
Customer Service Tool
Manual 35163
:
VariStroke Power Cylinder
Manual 82715:
Guide for Handling and Protection of Electronic Controls, Printed Circuit Boards, &
Modules
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System Description
The VariStroke-DX (dual-transfer) skid is a dual redundant hydraulic servo system which allows on-line
servo repairs and replacement. This skid utilizes two Woodward VariStroke-GI based servo valves
mounted on a single manifold assembly. The VariStroke-GI is a family of linear electrohydraulic actuators
that are designed to provide the linear actuation force to operate steam turbine control valves, valve racks
and Trip & Throttle Valves. This single-acting actuator family is intended for use on mechanical drive or
generator-drive steam turbines, and uses a low-pressure hydraulic oil source (typically turbine lube oil) to
provide its output shaft force. Refer to VariStroke-GI Product Specification 03464 for more information.
The VariStroke-DX skid is designed to be used in combination with Woodward’s single-acting VariStroke
Hydraulic Power Cylinders (VHPC). Refer to VHPC Product Specification 03465 for size and ordering
information.
The combined VariStroke-DX and VHPC system is specifically designed for use on critical steam turbine
applications where system uptime is essential. The utilized VariStroke-GI servos’ superb accuracy and
resolution make it ideal for steam turbine valve control. As a result of this servo’s integrated redundancy
and when used within the VariStroke-DX skid these servos can be repaired or replaced while the turbine
is on-line operating normally ensuring a high level of system reliability and availability.
VS
-
DX
Dual Transfer Skid
can be used also in other applications.
Contact with Woodward for more information and guidance for use in
different systems other than that described within this document.
The “
Master/Slave”
indication shows only which unit is designated for
primary operation from the control system. Because it is possible for
the slave to be in control, it is necessary to confirm which unit is
controlling the skid output via the external gages and the “In Control”
discrete output status.
For a full description of the VS-GI, see Woodward manual
35119
.
For the online
VS
-
G
I replacement procedure, see Woodward manual
35133.
The VS-DX Duplex Hydraulic Servo Skid precisely and stable control steam turbine actuation system
position proportional to the (4 to 20) mA input current signal. The system described in this manual
consists of a skid-mounted arrangement of two VS-GI’s operating through a transfer valve assembly as
shown in Figure 1-1.
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Figure 1-1. Basic VS-DX Application and Configuration
Designed as a stand-alone skid, servo-to-servo communication and automatic failover logic is included
within each servo forcing automatic transfers to the healthy servo with no external control logic or
interface required. Optionally, users can use a local switch or control driven relay connected to the skid to
routinely select and switch servo functions as the master and as the slave.
The VS-DX uses a specially designed fast-switching high signal select valve to ensure minimal control
switchover time and minimal system control pressure disturbance. During normal operation the In Control
servo will control the position of the connected VariStroke Hydraulic Power Cylinder (VHPC), while the
Not In Control servo is held in a standby mode with its pressure output port connected to the skid’s output
drain line. In this state, if the In Control servo or its input demand signal fail, the servo’s output is stepped
to a failsafe zero pressure level, the Not In Control servo is switched to an In Control state and begins
trying to control the VHPC, and the skid’s specially designed high signal select valve is then hydraulically
forced to connect the now healthy and In Control servo to the VHPC hydraulic pressure line.
Design Characteristics
The skid assembly has been designed to offer maximum reliability, especially for critical steam turbine
applications, and features include:
•Ease of installation
•Minimum hydraulic connections, reducing the potential for oil leakage
•Compact design
•Rapid control switchover (transfer) time
•2 (two) Isolation valves which allow each VS-GI to be fully calibrated and checked before switching it
to on-line service
•Dirt tolerant servos and shuttle valve
•Online diagnostics and automatic switchover logic
•Online replacement capability to safely and reliably disable, remove or replace the one of the VS-GI
without the need to stop the turbine or control system.
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Construction
The VS-DX is a complete packaged and tested assembly which consists of two Woodward VariStroke-I
servos (VS-GI’s) connected together to a single manifold with all interconnect piping, gauges and wiring
included and factory tested.
The two VS-GI’s are mounted to an anodized aluminum manifold containing the transfer valve, isolation
valves, pressure gauges, needle valves, shuttle valve subassembly and electrical junction box. The VS-
DX skid provide mounting interface on the bottom surface via four (4) threaded holes (see Figure 1-5).
Figure 1-2. VS-DX Main Components (Junction Box Version).
The complete assembly is designed for use in a hazardous environment, see the Regulatory Compliance
specifications for more details.
Integrated oil pressure gauges allow the user to visually verify which VS-GI is in control and verify the
VS-DX output oil header pressure level. The VS-GI discrete output status contacts can also be used to
provide verification of operation or shutdown via status lamps and/or the plant DCS to assist with system
health monitoring.
The hydraulic ports are represented on each VS-GI servo as SUPPLY for the supply oil port, DRAIN for
the drain (tank) lines, and on a common VS-DX manifold CONTROL for the control oil connection, DRAIN
for the drain (tank) line as shown in Figure 1-3 to Figure 1-10.
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Figure 1-3. VariStroke-DX, Junction Box Version, front view
Figure 1-4. VariStroke-DX, Junction Box Version, Top View
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Figure 1-5. VariStroke-DX, Junction Box Version, Bottom View
Figure 1-6. VariStroke-DX, Junction Box Version, Back View
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Figure 1-7. VariStroke-DX, Junction Box Version, Side View
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Figure 1-8. VariStroke-DX, Without Junction Box Version, Front View
Figure 1-9. VariStroke-DX, Without Junction Box Version, Rear View
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Figure 1-10. VariStroke-DX, Without Junction Box Version, Bottom View
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Chapter 2.
System Specifications
Table 2-1. Environmental
Ambient Temperature:
Without Junction Box –40 to +85°C (-40 to + 185⁰F)
With Junction Box –30 to +85°C (-22 to + 185⁰F)
Oil Temperature:
+15 to +70°C (+59 to 158⁰F) continuous
Oil Viscosity: 10 to 55 centistokes
Vibration: US MIL-STD 810F, M514.5A, Cat. 4 (0.015 G²/Hz, 10 to 500 Hz,
1.04 Grms)
Shock: US MIL-STD-810C method 516.2, procedure 1 (10 G Peak, 11 ms
duration, saw tooth)
Ingress Protection: IP66 per IEC EN 60529 with IECEx conditioning as described by
IEC 60079-0:2011 and IEC 60079-15:2010 PENDING IECEx
certification
Table 2-2. Physical
Height x Width x Depth:
Approx. (725.7 x 968.2 x 632.0) mm / (28.51 x 38.12 x 24.88) inch
Weight: Approx. 184 kg (405 lbs) without oil
Mounting: 4x .625-11 UNF threaded holes (see Figure 1-5)
Table 2-3. Electrical Specifications
Connections:
Electrical box terminals suitable for:
(0.14 to 6) mm² / (26 to 10) AWG stranded wire (power and ground
terminals)
(0.2 to 4) mm² / (24 to 12) AWG stranded wire (communication signal
terminals)
Junction box Cable Entries: 4 x 3/4 NPT CONDUIT HUB
Supply Voltage (18 to 32) V (dc), 24 V (dc) nominal (recommended cable size
6 mm² / 10 AWG)
Grounding connections: PE ground (recommended cable size 6 mm² / 10 AWG)
Hold-up time: 7 ms @ 2 A (dc) LAT current
Current Consumption: 2.3 A (MAX) at steady state @ 24 V 10 A transient (100 ms maximum)
Demand Signals #1, 2: (4 to 20) mA into 200 Ω. >70 dB CMRR. Common Mode Voltage Range
±50 V (dc), Accuracy 0.1% of full scale @ 25 °C
Cylinder Position
Feedback Signals #1, 2:
(4 to 20) mA into 235 Ω. >70 dB CMRR
Common Mode Voltage Range ±50 V (dc), Accuracy 0.1% of
full scale @ 25 °C
Analog Output Signal (4 to 20) mA. Maximum external load: 500 ΩAccuracy ±0.5 % of full
scale @ 25 °C
Discrete Output Signal Configurable for NO or NC,
0.5 A at 24 V (dc), max. 32 V (dc)
0.5 A inductive at 28 V (dc) 0.2 Henry
Discrete Input Signal: Contact current 3.8 mA (typ.) @ input closed
Max input voltage 32 V (dc), High signal threshold > 7 V; Low signal
Threshold < 3 V
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Table 2-3. VS-DX without Junction Box Version (to Each VS Unit)
Supply Voltage: (18 to 32) V (dc), 24 V (dc) nominal (use cable at least
1.5 mm² / 16 AWG)
Hold-up time: 7 ms @ 2 A (dc) LAT current
Current Consumption: 2.3 A (MAX) at steady state @ 24 V 10 A transient (100 ms maximum)
Demand Signals #1, 2: (4 to 20) mA into 200 Ω. >70 dB CMRR. Common Mode Voltage Range
±50 V (dc), Accuracy 0.1% of full scale @ 25 °C
Hold-up time: 7 ms @ 2 A (dc) LAT current
Current Consumption: 2.3 A (MAX) at steady state @ 24 V 10 A transient (100 ms maximum)
Demand Signals #1, 2: (4 to 20) mA into 200 Ω. >70 dB CMRR. Common Mode Voltage Range
±50 V (dc), Accuracy 0.1% of full scale @ 25 °C
Cylinder Position
Feedback Signals #1, 2: (4 to 20) mA into 235 Ω. >70 dB CMRR Common Mode Voltage Range ±50 V (dc), Accuracy 0.1% of full scale @ 25 °C
Analog Output Signal (4 to 20) mA. Maximum external load: 500 ΩAccuracy ±0.5 % of full scale
@ 25 °C
Discrete Output Signal Configurable for NO or NC,
0.5 A at 24 V (dc), max. 32 V (dc)
0.5 A inductive at 28 V (dc) 0.2 Henry
Discrete Input Signal: Contact current 3.8 mA (typ.) @ input closed
Max input voltage 32 V (dc), High signal threshold > 7 V; Low
signal Threshold < 3 V
Cable Entries: Analog: 0.750”-14 NPT
Power: 0.750”-14 NPT
CAN: 0.500”-14 NPT
Spare: 0.500”-14 NPT
Grounding Connections: PE Ground; Frame or Chassis Ground
Table 2-4. Cylinder Position Sensor Requirements
Output Signal:
Analog: 4–20 mA
Input Voltage: 15 V (dc) (power provided by VariStroke)
Linearity: ±0.04% Full Stroke
Current Drain: <100 mA
Sensor Length: ≤2 times the Cylinder Stroke Length
Update Rate: ≤1 ms
Sensor Cable Length Limit: 10 m (32.8 feet) maximum between sensor and VariStroke
Slower update rates than the one shown in the above
requirements
could result in excessive limit cycle, wear, and poor position
accuracy.
It is for this reason that Woodward does NOT recommend using a
combination of LVDTs and Signal Conditioners. This combination
will typically result in unacceptable delays in the position sensor
update rate.
Woodward recommends that the installer consider
Magnetostrictive position sensors and/or DCDTs.
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Table 2-5. Hydraulic Specifications
Hydraulic Supply Ports:
1.25 SAE J518 Code 61 Flange (x2) (on Servo “A”& “B”)
Hydraulic Drain Ports: 1.5 SAE J518 Code 61 Flange (x2) (on Servo “A”& “B”)
1.0 SAE J518 Code 61 Flange (on VS-DX Skid manifold)
Note:
SAE J518, JIS B 8363, ISO/DIS 6162 AND DIN 20066 are interchangeable, except for bolt
sizes/threads. The VS-DX uses metric bolt sizes.
Maximum Input/Supply Pressure: 34.5 barg (500 psig)
Minimum Input/Supply Pressure
(2)
(above drain line pressure):
3.45 barg (50 psig)
(
2
)
Minimum
Input/Supply
pressure above drain pressure (
Supply
Pressure – Drain Pressure < 3.45 bar (g) (50 psig).
It is highly recommended to maintain drain pressure level as low
as possible to avoid operating issues with single acting type
cylinders.
It is highly recommended that inlet supply pressure not be allowed
to decrease by more than 10% of nominal value during slew/step.
It is recommended to set hydraulic system pressure regulator to
110% or less of normal operating pressure to prevent over-
pressure.
Tank Pressure: Drain pressure must not exceed 10% of supply pressure or 3.4
bar (50 psig), whichever is less, under any condition.
Recommended Fluid: Mineral or synthetic based oils may be used. Woodward oil
recommendations per manual 25071.
Oil Cleanliness: ISO 4406:99 code 20/18/16 max fluid cleanliness or better is
recommended for optimum reliability.
Figure 2-1. VariStroke-DX, Hydraulic Schematic
Released