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AUTOMATIC VOLTAGE REGULATOR (AVR)
NISHISHIBA ELECTRIC CO., LTD.
New product
The NISHISHIBA VZKUP-4B(P1) is a solid-state Automatic Voltage Regulator used in generator excitation systems to maintain stable generator terminal voltage as electrical load changes.
The exact unit shown here is clearly identified as:
Manufacturer: NISHISHIBA ELECTRIC CO., LTD.
Type: VZKUP-4B(P1)
Product: Automatic Voltage Regulator (AVR)
Rating: 450 V / 5 A / 60 Hz
Country of Origin: Japan
Application: AC Generator Excitation & Voltage Regulation
System: Marine / Industrial Generator
Independent listings of genuine VZKUP-4B(P1) units also document the same 450 V, 5 A, 60 Hz configuration.
The AVR continuously compares generator terminal voltage with its reference value and adjusts excitation so generator output voltage remains stable as load changes.
Nishishiba generator documentation describes the AVR as regulating the exciter field current to maintain generator terminal voltage at a constant value regardless of load. External voltage adjustment can also be incorporated into the generator-control arrangement.
A simplified operating chain is:
Generator Voltage → AVR Sensing → Voltage Error Detection → Excitation Adjustment → Exciter Field → Generator Voltage Correction
This function is critical because shipboard generators must maintain reliable voltage while motors, pumps, compressors, thrusters and other loads are connected and disconnected.
The front terminal markings on this AVR identify several important circuits:
Sensing Voltage: U – V – W
Power Input: U1 – V1 – W1
Output: J – K
Current Input: C1 – C2
Differential / Cross Current Output: C3 – C4
External Voltage Adjustment: 1 – 3 – E
The front panel also includes DAMPING adjustment points.
These functions show that the regulator is designed for more than simple stand-alone voltage control; it can form part of a generator system requiring cross-current compensation and external voltage adjustment.
Typical functions associated with the VZKUP generator AVR arrangement include:
Nishishiba identifies the AVR generally as essential generator voltage-control equipment and continues to offer modern digital AVR solutions for power-generation systems.
One of the most important SEO and sourcing points is that VZKUP does not mean only one AVR specification.
Verified marine-generator documentation and market references show several related designations.
This is the exact family shown in the supplied photograph. Published units include 450 V, 5 A, 60 Hz configurations.
Another documented VZKUP-4B configuration, also found on Nishishiba marine generator installations with 450 V / 60 Hz generators.
Nishishiba generator drawings document VZKUP-4A(P8) on 450 V / 60 Hz marine AC generator installations.
A Nishishiba AVR instruction manual is publicly indexed for Type VZKUP-4C0, documenting another VZKUP-family variation.
Important: VZKUP-4A, VZKUP-4B(P1), VZKUP-4B(P8) and VZKUP-4C0 should not automatically be considered interchangeable. Generator specification, excitation arrangement, wiring, rating and complete type designation must be checked.
A buyer may search for “Nishishiba AVR” without knowing the exact family. For this reason, related Nishishiba AVR series are also relevant to this article.
Documented families include:
VZRAB-1A1
VZRAB-1S
VZRAB-1S(P)
VZRAB-1S(PT)
VZRAB-4AP / 4APR / 4APT / 4APTR
VZRAB-4AS / 4ASR / 4AST / 4ASTR
VZDUP-2A Series
VZKUP Series
These are related Nishishiba voltage-regulator families, not automatic replacements for the VZKUP-4B(P1).
Nishishiba manufactures brushless AC generators specifically for marine service, covering low-voltage systems beginning at AC 450 V and extending into medium-voltage applications. Diesel- and turbine-driven generator configurations are supported.
A VZKUP-type AVR can therefore be encountered in:
Main Diesel Generators • Auxiliary Generators • Marine AC Generators • Generator Switchboards • Static Excitation Systems • Parallel Generator Installations
Typical vessels include:
Bulk Carriers • Container Ships • Oil Tankers • Chemical Tankers • LNG/LPG Carriers • General Cargo Ships • Offshore Vessels • Ferries • Passenger Ships • Dredgers
The AVR works together with generator sensing, excitation and switchboard control equipment.
For generators operating in parallel, the current-input and cross-current circuitry can participate in reactive-load-sharing arrangements. Nishishiba marine generator documentation specifically shows cross-current compensating circuits associated with VZKUP installations.
Check:
Possible causes include sensing-circuit failure, external voltage-adjustment problems, AVR component failure or incorrect regulator adjustment.
Inspect:
A compatible VZKUP-4B technical manual specifically documents stability, voltage, power-factor and under-frequency adjustments on replacement implementations.
Check:
Do not immediately assume the AVR is defective. Check the complete excitation system, residual/PMG source where applicable, exciter, rotating rectifiers, wiring and generator condition.
Burnt components, overheated terminals or capacitor damage may indicate an external fault. The generator and excitation circuit should be inspected before installing another AVR.
The photographed VZKUP unit itself states:
“SOLID STATE DEVICE – DO NOT MEGGER OR HIPOT.”
It also warns against incorrect wiring, short-circuiting specified AVR terminals and changing internal settings while the generator is rotating.
These precautions are important because inappropriate insulation/high-voltage testing through connected AVR electronics can damage solid-state components.
SM MARINE SERVICE™ can support sourcing of:
NISHISHIBA VZKUP-4B(P1) • VZKUP-4B(P8) • VZKUP-4A • VZKUP-4A(P8) • VZKUP-4C0 • VZRAB Series • VZDUP Series • Complete AVR Units • AVR PCB / Electronic Components • Voltage-Adjusting Rheostats • Cross-Current CTs • Static Excitation Components • Generator Excitation Spare Parts
Equipment may be available as:
New • New Old Stock • Used • Tested Working • Refurbished • Reconditioned
For accurate replacement, please send:
AVR Type + Full Rating + Generator Maker + Generator Type + Generator kVA + Voltage + Frequency + Front/Rear Photograph + Terminal Arrangement + Existing Drawing Number
Matching only the word “VZKUP” is not enough.
SM MARINE SERVICE™ also lists another Nishishiba generator AVR:
NISHISHIBA VZRAB-4A(PT)DSGS Automatic Voltage Regulator
This creates a direct internal link between the VZKUP and VZRAB Nishishiba AVR families.
TAIYO EXU-61A Automatic Voltage Regulator – Marine Generator Excitation System Guide
TAIYO EXU-61A is another important legacy marine generator AVR. Replacement references also group several Taiyo and Nishishiba compound-generator AVR families within the same marine voltage-regulation market, although individual models must be matched technically.
TAIYO AVR – Marine Generator Voltage Regulator
This internal link is useful for buyers who know the generator maker but do not yet know the exact regulator model.
BASLER ELECTRIC SR8A-2B15B3A Static Voltage Regulator
Basler static voltage regulators are another important category of generator excitation equipment used in marine and industrial power-generation systems.
BASLER ELECTRIC SSR 125-12 Static Voltage Regulator
Connecting these AVR pages helps users searching not only Nishishiba but also Basler generator excitation and voltage-control equipment.
CATERPILLAR VR6 Automatic Voltage Regulator
The Caterpillar VR6 page extends the internal AVR category to generator owners searching by engine/generator brand.
SM MARINE SERVICE™ also supports several Taiyo Electric AVR models:
TAIYO ASC-32-4Z4 Automatic Voltage Regulator
TAIYO ELECTRIC ASC-62-2 Automatic Voltage Regulator
Taiyo Electric ASC-32-424 Automatic Voltage Regulator
Together with NISHISHIBA VZKUP, VZRAB, TAIYO EXU/ASC, BASLER SR/SSR and CATERPILLAR VR6, these pages create a much stronger internal Marine Generator AVR & Excitation System cluster.
Even when the exact model is not listed, SM MARINE SERVICE™ can assist with sourcing marine generator AVR equipment from different manufacturers and legacy generator systems.
Common enquiry information should include:
AVR Maker • AVR Model • Full Nameplate • Generator Maker • Generator Model • kVA Rating • Output Voltage • Frequency • Excitation Type • Connection Diagram
This is especially useful when searching obsolete or discontinued marine regulators.
Many operational ships continue using original generators for decades.
When an AVR fails, replacing the entire generator or excitation system may require major engineering work. Correctly sourcing or repairing the existing regulator can avoid unnecessary changes to:
Generator Wiring • Exciter • Current Transformers • Switchboard • Parallel-Operation Circuit • Voltage Adjustment • Protection System
For this reason, legacy models such as VZKUP, VZRAB, EXU, ASC, SR8A, SSR and VR6 remain commercially important marine spare parts.
It is an Automatic Voltage Regulator used with compatible Nishishiba generator excitation systems to maintain stable generator terminal voltage.
The supplied nameplate shows:
450 V • 5 A • 60 Hz
The same rating is independently documented on other genuine VZKUP-4B(P1) units.
On the photographed AVR they are identified as the Sensing Voltage terminals.
They are identified as the Power Input terminals.
They are the AVR Output connections associated with the excitation circuit.
They are identified as Current Input terminals.
The panel identifies them as Differential / Cross Current Output connections, relevant to generator parallel-operation circuitry.
They belong to the same broader VZKUP-4B family, but their suffixes are different and they should not be assumed interchangeable without checking the original generator and AVR documentation. Both versions are documented in the marine spare-parts market.
Yes. Nishishiba generator documentation identifies VZKUP-4A(P8) in a 450 V, 60 Hz generator installation.
Yes. Nishishiba, Taiyo, Basler, Caterpillar and other marine generator/excitation-system AVR requirements can be sourced subject to model and availability.
SM MARINE SERVICE™ supports international sourcing of legacy and current marine generator AVR equipment, subject to stock availability.
The NISHISHIBA VZKUP-4B(P1) Automatic Voltage Regulator is a solid-state generator excitation regulator used for maintaining stable terminal voltage on compatible marine AC generators. The photographed unit is rated 450 V, 5 A, 60 Hz and includes voltage sensing, excitation power input, AVR output, current input, cross-current compensation and external voltage-adjustment connections. SM MARINE SERVICE™ supports worldwide sourcing of VZKUP-4B(P1), VZKUP-4B(P8), VZKUP-4A, VZKUP-4C0, VZRAB, VZDUP and other marine generator AVR equipment, subject to compatibility and availability.
A Nishishiba instruction manual is publicly indexed for the VZKUP-4C0 family and covers:
Type Symbol • Specifications • Maintenance • AVR Operating Principle • Block Diagram • Variable Resistors • Connection Diagram • Troubleshooting
View NISHISHIBA VZKUP AVR Instruction Manual Reference
Because this manual is for a related VZKUP configuration rather than the exact photographed VZKUP-4B(P1) revision, wiring/settings should not be copied without verifying the vessel's specific documentation.
A replacement-manufacturer technical manual specifically covers NISHISHIBA VZKUP-4B / VZKUP-4B(P1) terminal arrangements and adjustment principles.
View VZKUP-4B Compatible AVR Manual
NISHISHIBA Marine Electrical Systems – Official Manufacturer Page
Marine Automation & Navigation Equipment Supplier
Available Condition:
• New Equipment • Used Equipment • Refurbished Equipment • Reconditioned Equipment
Stock Location:
• Bangladesh • China
Services:
• Worldwide Shipping • Technical Support • Spare Parts Supply • Marine Equipment Sourcing
Contact Information
SM MARINE SERVICE™ Samir Market, DT Road, Pahartali, beside CDA Market, Chattogram, Bangladesh
Mobile / WhatsApp / Viber: +88 01818 929292
Email: info@smmarineservice.com
Website: www.smmarineservice.com
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