Techcross BWTS Troubleshooting. Complete Operating Logic and TRO Troubleshooting Guide

Greetings! In this article, we'll discuss the Techcross BWTS (ECS) ballast system, its operating logic, and troubleshooting instructions from the Korean manufacturer.

The Electro-Cleen System (ECS) by Techcross is an electrochlorination-type Ballast Water Treatment System (BWTS). It disinfects ballast water during uptake by generating sodium hypochlorite (NaOCl) from seawater and neutralizes residual oxidants during discharge to comply with IMO D-2 regulations.

This article explains:

• The complete operating logic of the system
• Functional sequence in Ballasting and De-ballasting modes
• Control philosophy
• A structured TRO troubleshooting algorithm

System Working Principle

Techcross ECS is a side-stream electrochlorination system.

Core Concept:

• During ballasting → active substance (NaOCl) is generated and injected.
• During de-ballasting → residual oxidants are neutralized.

Main Components

1. Ballast Water Filter (typically 40 μm)
2. Side-stream Electrolysis Unit
3. Power Supply Unit (PSU)
4. Hydrogen Ventilation System
5. TRO Analyzer
6. Neutralization Unit (Na₂S₂O₃ dosing)
7. Salinity Sensor
8. Flow Meter / Flow Switch
9. PLC Control Panel (HMI)

Techcross PLC Control Panel (HMI)

Power Supply Unit (PSU)

Complete Operating Logic

A. Ballasting Mode (Treatment Mode)

Step 1 – Start Conditions

The system will start only if:

• Ballast pump running signal is present
• Flow rate above minimum threshold
• Salinity > 1 PSU
• No active critical alarms
• Hydrogen ventilation operational

If any interlock fails → electrolysis will not start.

Step 2 – Filtration

All ballast water passes through the automatic filter:

• Organisms > 40 μm removed
• Differential pressure monitored
• Automatic backflush activated when required

Step 3 – Electrolysis (Active Substance Generation)

A portion of seawater is diverted into the electrolysis cell.

Chemical reaction: NaCl + H₂O + electricity → NaOCl + H₂

Produced:

• Sodium hypochlorite (disinfectant)
• Hydrogen gas (vented safely)

Hydrogen gas sensor

Step 4 – Injection and Mixing

Generated NaOCl is injected into the main ballast line. PLC controls:

• DC current
• Output capacity
• TRO setpoint

Typical TRO during ballasting: 6–10 mg/L (model dependent)

Step 5 – TRO Feedback Control Loop

The TRO analyzer measures Total Residual Oxidant.

Control logic:

• If TRO low → increase DC current
• If TRO high → decrease DC current

Closed-loop automatic regulation ensures proper dosage.

Step 6 – Holding Time

After tank filling:

• Minimum 24 hours holding time required
• Allows full inactivation of microorganisms < 10 μm.

B. De-ballasting Mode (Neutralization Mode)

Electrolysis is OFF.

Step 1 – Residual TRO Measurement

Water in ballast tank may contain remaining oxidants.

Regulatory discharge limit: ≤ 0.1 mg/L TRO

Step 2 – Neutralization

Sodium thiosulfate (Na₂S₂O₃) is injected.

Chemical reaction: NaOCl + Na₂S₂O₃ → neutralized compounds

Step 3 – Final TRO Monitoring

TRO is measured at discharge line.

If above limit: dosing rate increases automatically.

Techcross BWTS TRO

5. Control Philosophy Summary

The system will not operate if:

• No flow
• Low salinity
• Hydrogen ventilation failure
• TRO sensor failure
• Electrolyzer overcurrent
• PSU overheating
• PRU (Power Rectifier Unit) overheating

Power Rectifier Units

PRU Communication Fail (burned transistor and diode). Possible cause: insufficient system cooling

PRU Heatsink Temperature High (cleaning and tightening contacts)

Safety interlocks are integrated at PLC level.

TRO Troubleshooting Algorithm

TRO-related faults are the most common. We divide them into:

• LOW TRO
• HIGH TRO

A. LOW TRO During Ballasting

Step 1 – Check Electrolysis Current

Observe HMI:

• DC Current (A)
• DC Voltage (V)

If current = 0 or very low:

• → Check PSU
• → Check interlocks
• → Check contactors and protection devices

Relays

Step 2 – Check Salinity

If salinity < 1 PSU: system cannot generate sufficient NaOCl.

Verify:

• Salinity sensor reading
• Manual refractometer measurement

Step 3 – Check Side-Stream Flow

Insufficient flow through electrolyzer:

• Blocked strainer
• Closed valve
• Air lock
• Low pressure

Flow sensor

Step 4 – Inspect Electrolysis Cell

Possible issues:

• Scaling
• Fouling
• Worn electrodes
• Internal blockage

Cleaning may be required.

Step 5 – Verify TRO Analyzer

Most frequent cause of LOW TRO alarm.

Check:

• Flow cell contamination
• Air bubbles
• Membrane condition
• Calibration date

Perform manual DPD test.

If manual test normal but sensor low → sensor malfunction.

B. HIGH TRO During Ballasting

Step 1 – Check Flow Rate

• Reduced ballast flow increases concentration.
• Verify actual flow vs design.

Step 2 – Check Feedback Loop

If TRO sensor slow or frozen:

• System continues generating.
• Recalibrate sensor.

Step 3 – Check Mixing Quality

Improper injection point may cause localized high readings.

C. LOW TRO During Discharge

Means insufficient neutralization.

Check:

• Na₂S₂O₃ tank level
• Dosing pump stroke
• Injection line blockage
• Check valves

Dosing pumps

D. HIGH TRO During Discharge (Critical Situation)

High PSC risk.

Immediate checks:

• Neutralizer tank level
• Dosing pump operation
• TRO sensor calibration
• Manual DPD verification

If manual reading normal → analyzer fault.

7. Practical Field Diagnostic Logic

LOW TRO?

Is DC current present?

• NO → PSU / interlock issue
• YES → Is salinity sufficient?
• YES → Is side-stream flow adequate?
• YES → Is electrolyzer clean?
• YES → Is TRO sensor calibrated?

HIGH TRO?

• Is ballast flow stable?
• Is TRO sensor reliable?
• Is mixing adequate?
• Is neutralization working?

8. Most Common Real-Life Causes

1. Dirty TRO analyzer
2. Low salinity water
3. Incorrect calibration
4. Side-stream blockage
5. Electrolyzer scaling

Techcross ECS BWTS is a robust electrochlorination system built around:

• Side-stream active substance generation
• Closed-loop TRO control
• Automatic neutralization during discharge

Understanding the control logic and TRO feedback mechanism allows engineers to diagnose 90% of operational problems efficiently.

Thank you for your attention! I hope this article was useful.

Manuals! As always, I'd like to draw your attention to the manufacturer's official instructions. This article was written based on the instructions and my personal experience. If you need manuals for the BWTS Techcross, I recommend our closed Telegram channel "Marine Engineering Manuals." In this channel, you'll find not only all the necessary manuals and troubleshooting service manuals, but also video tutorials on how to operate the BWTS Techcross.

If you encounter any issues with this ballast system, please let me know in the comments, and I'll try to help. By the way, there's a helpful article on our website: "ERMA First BWTS. Simple Instructions for Using a Ballast System". It also describes a similar BWMS system with electrolysis.