The right servo stabilizer KVA is determined from the actual electrical load rather than from machine name alone. Collect the connected or simultaneous load, rated current, phase, motor or compressor starting information, minimum and maximum site voltage and required output conditions. Use those values to evaluate the stabilizer capacity and input range.
Step 1: List the Equipment Connected to the Stabilizer
Start by listing every machine or electrical load that will actually receive power through the stabilizer. If one stabilizer will supply several machines, identify which of them can operate at the same time.
Record the rating available on the machine nameplate or electrical documentation. Depending on the equipment, this may be shown in kW, HP, ampere, KVA or a combination of these values.
- Equipment name
- Quantity
- Rated kW, HP, ampere or KVA
- Single-phase or three-phase
- Whether all loads operate simultaneously
Step 2: Understand kW and KVA
Stabilizers are commonly rated in KVA, which represents apparent power. If the equipment documentation gives both kW and power factor, apparent power can be estimated using KVA = kW / power factor.
Do not automatically assume one power factor for every machine. Use the equipment documentation, electrical measurements or qualified technical guidance where possible.
For motor ratings stated in horsepower, 1 HP is approximately 0.746 kW, but the motor electrical input and starting characteristics should still be checked rather than sizing only from mechanical horsepower.
Step 3: Check Motor and Compressor Starting Demand
Motors and compressors can draw more current during starting than during normal running. The actual starting demand depends on the motor, starting method, drive and connected mechanical load.
This is why one universal 25%, 30% or 50% margin should not be applied blindly to every installation. A machine with a variable-frequency drive, soft starter or direct-on-line starter can have different starting characteristics.
- Motor or compressor rating
- Starting method
- Rated current
- Starting sequence
- Whether several motors can start together
Step 4: Measure the Minimum and Maximum Input Voltage
KVA is only part of stabilizer selection. The unit also needs an input-voltage range suitable for the actual supply at the installation.
Record the lowest and highest incoming voltage when the plant is operating normally and when the voltage problem is observed. For a three-phase system, a qualified electrician should take the appropriate phase measurements safely.
Do not choose an input range from a city name or generic assumption. Two installations in the same industrial area can have different electrical conditions.
Step 5: Confirm Phase and Required Output
The stabilizer phase arrangement must match the connected equipment and supply. The required output voltage should also be confirmed from the machine or electrical system documentation.
KEVOR single-phase Servo capability extends from 1 KVA to 60 KVA, while three-phase capability starts from 10 KVA and extends to 100 KVA. For overlapping capacities such as 10–30 KVA, the phase should be selected according to the supply and load.
Individual Stabilizer vs Central Stabilizer
One central stabilizer can sometimes supply multiple machines when the total simultaneous load, starting demand, electrical distribution and phase arrangement are suitable.
Individual stabilizers may also be appropriate where machines have different voltage requirements, are installed in separate areas or should be electrically separated for operational reasons.
The decision should be based on the plant distribution and machine requirements rather than a universal rule that one arrangement is always better.
Four Details to Start a KEVOR Servo Enquiry
If you do not know the final KVA, you can still start the enquiry. The following four details are often enough to begin reviewing the requirement.
- Connected load or machine nameplate details
- Single-phase or three-phase
- Minimum and maximum incoming voltage
- Machine or application type