Why Does Screw Pump Current Increase? The Hydraulic Reasons Behind It

 Why Does Screw Pump Current Increase? The Hydraulic Reasons Behind It

In many industrial applications, when the operating current of a screw pump rises, the first reaction is often:

👉 “There must be something wrong with the motor.”

But in reality:

👉 In most cases, the motor is not the problem — the system is.

To put it simply:

👉 Higher current means the pump is working harder, not that the motor is failing.

1. What Does Current Actually Represent?

A screw pump is a positive displacement pump.

👉 The motor current reflects the torque required to overcome system resistance

So:

Higher resistance → higher torque → higher current

👉 The key question is:

👉 What is increasing the hydraulic load?

2. Common Hydraulic Causes of Increased Current

2.1 Increased Discharge Pressure (Most Direct Cause)

If the system experiences:

Partially closed discharge valve

Pipeline blockage

Increased system resistance

👉 Discharge pressure rises

For screw pumps:

👉 Higher pressure directly means higher load

Result:

👉 Motor current increases accordingly

2.2 Increased Fluid Viscosity (Often Overlooked)

Changes such as:

Lower temperature

Higher concentration

Process variation

👉 Lead to higher viscosity

This results in:

Increased internal friction

Greater resistance during transport

👉 The motor must deliver more torque → current rises

2.3 Poor Suction Conditions (Hidden Load)

If the suction side has:

Clogged filters

Long suction pipelines

Excessive suction lift

👉 The pump struggles to fill properly

Result:

👉 The pump works inefficiently but consumes more energy

👉 Current may increase abnormally

2.4 Gas Content in the Fluid (Unstable Load)

If gas enters the system:

Air leakage on suction side

Gas-containing media

👉 Causes unstable flow conditions

Typical symptoms:

Fluctuating current

Occasional spikes

2.5 Internal Hydraulic Changes

Changes in internal conditions such as:

Clearance variation

Sealing performance

Can affect:

👉 Energy distribution inside the pump

Sometimes leading to:

👉 Higher current but lower efficiency

3. A Key Insight

👉 Higher current does not always mean higher output

In many cases:

👉 It indicates energy loss and inefficiency

In other words:

👉 The motor is working harder, but not more effectively

4. Practical Troubleshooting Tips

You can quickly identify the issue by observing:

✔ Pressure increase + current increase → system resistance issue

✔ Temperature change + current change → viscosity effect

✔ Fluctuating current → gas involvement

✔ Reduced flow + higher current → hydraulic inefficiency

5. Engineering Insight

In real projects, a common mistake is:

👉 Checking the motor first, instead of the system

Typical sequence:

Replace motor → no improvement

Replace components → still unresolved

Final conclusion:

👉 The system conditions were the real cause

Experienced engineers usually focus on:

Changes in discharge pressure

Fluid properties

Suction conditions

👉 Because:

👉 These define the actual load on the pump

6. Further Reference

If you are troubleshooting similar issues, you can refer to:

👉 https://www.scpv.cn/news/387.html

This resource provides additional insights into screw pump operation and common problems.

Conclusion

An increase in screw pump current is not just an electrical issue.

👉 It is primarily a hydraulic issue.

Final takeaway:

👉 Current reflects load, and load comes from the system.

If you are experiencing:

High current

Overload conditions

Reduced efficiency

👉 Don’t just check the motor —

👉 Check what the system is forcing the pump to handle.