Electrical Appliances & Electrical Machines are made to work with optimum efficiency at rated voltage. They work at particular voltage range, it may be +-5% or +-10% of rated voltage. Voltage Out of the range leads to decrease in efficiency, decrease in useful life & malfunctioning in operation. 

System must work at defined voltage range; failure of this leads to overcurrent, overheating, degraded useful life, insulation Damage, reduced performance. Voltage stability is most important in electrical system That’s why for a stable voltage, voltage stabilizer is must. In this post, We are going to discuss the technical specifications of 25KVA Servo control voltage stabilizer. 

 

25KVA ASC Voltage Stabilizer Made by Fuji Electric

This 25KVA ASC (Automatic servo control voltage stabilizer) is having a size of 540*600*1075[L*B*H(mm)].

This stabilizer provides a stable 3phase 415V output voltage at an input voltage ranges from 360-460 V. Servo is equipped with HMI Which reflects input voltage, Output voltage, Input current, Output current & faults. Servo also contains a bypass switch.

Collage images of 25KVA ASC Voltage Stabilizer by Fuji Electric
25KVA ASC Voltage Stabilizer by Fuji Electric

What is a servo voltage stabilizer ? 

Servo voltage stabilizer utilizes the working principle of transformer to produce stable voltage. An input to the transformer is changed through variable variac with the help of servo motor. That’s why it is known as servo voltage stabilizer.

 

Technical specifications of voltage stabilizer 

 

HMI (Human Machine Interface)

HMI of ASC Voltage Stabilizer
HMI of 25KVA ASC Voltage Stabilizer by Fuji Electric

 

HMI has two displays

1st is VF meter for voltage & frequency
Input, Output & Hz(frequency) LEDs are present on this meter along with its phase representing LEDs Red, Yellow & blue.
We can also check phase & line voltages on both Input & Output sides by pressing set button continuously.
 
For example:
  • We press set button for 1st time, Input LED & red LED get on. This means display is showing the red phase voltage at Input side.
  • When we press set button for 7 times, output & red-yellow LEDs get on. This means display showing the line to line voltage between red & yellow phase at output side.
 
2nd is Ammeter for ampere(current) reading
Load current on all the three phase; can be checked on this 2nd display.
Red, yellow, blue LEDs are phase representing LEDs on one side of the display. 
 
These all the parameters Input phase voltage, Input line Voltage, Output phase voltage, Output line voltage, frequency & line current in all the three phases can be seen one by one by pressing MENU KEY continuously.
 

HMI of 25KVA ASC Voltage Stabilizer by Fuji Electric
HMI of 25KVA ASC Voltage Stabilizer by Fuji Electric | Push Button keys on HMI
Push Buttons/ keys
HMI has three buttons ‘MENU’, ‘START’, ‘STOP’.
There is two modes to operate these three keys which are RUN Mode & SET mode.
To enter into RUN mode there is no need to press any button because it is the default mode.
To enter into SET mode; press the 3mm tactile switch which is placed inside stabilizer cabin.
SET mode is used to change the parameters value on the other hand run mode is used in running conditions to select the parameter.”
 
Run mode- To switch off output load
Set mode- To edit the selected digit
 
Run mode- To switch on output load
Set mode- To select the digit
 
Run mode-To view the running parameters like voltage, current & frequency.
Set mode- To view the settings.
 
RUN mode- To view the error log in
SET mode- To calibrate the phase voltage & line voltage

HMI of 25KVA ASC Voltage Stabilizer by Fuji Electric
HMI of 25KVA ASC Voltage Stabilizer by Fuji Electric | Fault/Signal LEDs on HMI
 
FAULT/SIGNAL LEDs
On right side of HMI schematic diagram is present. Fault/signal LEDs are present on this diagram. LEDs for voltage on each phase is present on both input & output sides, These LEDs show whether voltage on the side is present or not.
 
OVL LED 
This LED is present on all three outputs which represents overload on each phase.
 
NEUTRAL/EARTH FAULT LED 
To indicate neutral fault condition.
 
PHR LED 
To indicate phase reversal.

 

PROTECTIONS

1. Electronic Over & under voltage trip with time delay for input & Output.
2. Electronic overload protection & short circuit protection through MCB.
3. Surge Arrester/ RF suppressor(optional)
4. Phase reversal protection & cutoff.
5. Single phase prevention & cut off.
6. Neutral failure protection
7. Frequency cut off protection.
8. Earth neutral voltage cut off protection.
9. MCB & Manual Bypass (A 3 pole 50 Amps MCB is installed for switching & short circuit protection. Stabilizer can be bypassed through a Manual BYPASS switch )

MCB & BYPASS switch on voltage stabilizer
25KVA ASC Voltage Stabilizer by Fuji Electric | MCB & BYPASS switch
 

CONNECTION BOX

Connection box is present at back downside of stabilizer.
1st left point is earth after that 3phase+ Neutral input points are present. Along side the input terminals, Output terminals are provided which are 3phases+Neutral.

Connection box ASC voltage stabilizer
HMI of 25KVA ASC Voltage Stabilizer by Fuji Electric | Connection terminals
 

Applications of 25kVA Servo Stabilizer

 

Frequently Asked Questions (FAQs)

Q1. What is a 25kVA servo voltage stabilizer used for?
A 25kVA servo voltage stabilizer is used to maintain a constant output voltage (usually 415V) despite input voltage fluctuations. It protects industrial equipment such as CNC machines, motors, panels, and sensitive electrical loads from overvoltage and undervoltage conditions.


Q2. What is the input voltage range of a 25kVA servo stabilizer?
The typical input voltage range of a 25kVA three-phase servo stabilizer is 360V to 460V. It automatically corrects the voltage and maintains a stable output for safe equipment operation.


Q3. How does an automatic servo voltage stabilizer work?
An automatic servo stabilizer continuously monitors the input voltage using a control circuit or microcontroller. When voltage fluctuates, a servo motor adjusts the variac (auto transformer) to increase or decrease the output voltage and maintain a constant level.


Q4. What protections are available in a servo voltage stabilizer?
Most servo stabilizers provide multiple protections such as:

These features help prevent equipment damage.


Q5. What is the efficiency of a servo voltage stabilizer?
A servo voltage stabilizer typically operates with high efficiency of around 97% to 98%, resulting in low power loss and reliable long-term performance.


Q6. Where is a 25kVA servo stabilizer commonly used?
It is widely used in:


Q7. Why is voltage stabilization important for industrial equipment?
Voltage fluctuations can cause overheating, insulation failure, reduced efficiency, and unexpected machine breakdown. A servo stabilizer ensures stable voltage, improves equipment life, and reduces maintenance costs.

 

SUMMARY

Stable voltage across the system increases its useful life. It also makes the system highly efficient.

For voltage stabilization, Voltage stabilizer are presents. Both in Single phase as well as 3 phase. There are multiple types of stabilizers working on different principles. In this post, 25KVA(ASC) Automatic servo control voltage stabilizer is been discussed. This stabilizer is made by fuji electric.

If you want to know about the working of servo, You can go through our next post whose link is given below:

Working principle of Servo Voltage Stabilizer

3 Responses

  1. Just press the start button for auto start & make sure selector switch position in Auto side(SCVC).2. Run mode is default mode, Servo always remains in Run mode in normal working conditions. If you want to enter in set mode, You have to switch on the tactile switch present inside the cabinet of servo; ON top most side.

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