The OMRON PWB (DCF) 1178253-6C is a DC Filter Board (Direct Current Filter Board) designed for OMRON KP100L, KP125L, and KP150L three-phase photovoltaic inverters.

This board plays a critical role in filtering electrical noise and high-frequency disturbances present on the DC side of the inverter. Utilizing high-current toroidal inductors, filter capacitors, and EMI suppression components, it helps stabilize the DC voltage coming from the photovoltaic array before it is processed by the inverter power conversion stages.

The DCF board also protects sensitive inverter electronics from voltage spikes, switching noise, electromagnetic interference, and transient disturbances generated by MPPT circuits and IGBT power modules.

⚙️ Technical Specifications

• Manufacturer: OMRON
• Model: PWB (DCF)
• Part Number: 1178253-6C
• Type: DC Filter Board
• Application: Grid-Tied Photovoltaic Inverters
• Compatibility:
  • OMRON KP100L
  • OMRON KP125L
  • OMRON KP150L
• Filter Technology:
  • DC-side EMI/RFI filtering
  • Electrical noise suppression
  • High-current toroidal inductors
  • High-voltage suppression capacitors
  • Transient protection circuits
• Dedicated connectors for integration with inverter power stages
• Internal inverter installation

🔧 Main Functions

DC Current Filtering

Reduces harmonic components and high-frequency noise generated by electronic switching operations within the inverter.

EMI Reduction

Limits conducted electromagnetic interference transmitted toward photovoltaic modules and internal inverter circuits.

MPPT Stage Protection

Protects maximum power point tracking circuits from electrical disturbances, voltage spikes, and transient events.

DC Bus Stabilization

Helps maintain a stable DC voltage supply feeding the inverter's IGBT power modules.

Power Electronics Protection

Reduces electrical stress on critical components, including:

• IGBT modules
• DC bus capacitors
• Power driver circuits
• Control electronics

🔌 Purpose and Operation

The DCF board ensures that the DC power generated by photovoltaic modules is properly filtered before conversion into AC power.

Its primary functions include:

• Elimination of high-frequency disturbances
• Reduction of electromagnetic interference
• Protection of power conversion stages
• Improvement of energy conversion quality
• Enhancement of inverter reliability and stability

Without this board, electrical noise and transient disturbances could negatively affect inverter performance and reduce the lifespan of power electronics.

🧩 Role Within the Inverter System

Inside OMRON KP Series inverters, the DCF board is installed between:

• PV array DC inputs
• MPPT stages
• Main DC bus
• Power conversion modules

It serves as a key component within the DC power path and directly contributes to the stability and reliability of the entire inverter system.

⚠️ Typical Faults and Symptoms

Damaged Inductors

Symptoms:

❗ Unusual electrical noise
❗ Excessive heating
❗ Reduced inverter efficiency

Degraded Filter Capacitors

Symptoms:

❗ Increased DC bus ripple
❗ Operational instability
❗ Random inverter shutdowns

Short Circuits in Filter Components

Symptoms:

❗ Blown fuses
❗ Startup failures
❗ Damage to power stages

Oxidized or Damaged Connections

Symptoms:

❗ Voltage drops
❗ Intermittent faults
❗ Reduced power production

Lightning or Surge Damage

Symptoms:

❗ Burned components
❗ Permanent board failure
❗ Immediate inverter shutdown

🚨 Possible Associated Errors

When the DC Filter Board develops faults, the inverter may generate errors such as:

• DC Bus Fault
• DC Voltage Error
• Input Voltage Fault
• MPPT Fault
• Ground Fault
• Internal Hardware Error
• Isolation Fault
• DC Ripple Error
• Overcurrent DC
• Power Stage Fault
• Internal Protection Triggered

Error messages may vary depending on inverter firmware version and configuration.

🛠 Applications

• Repair of OMRON KP Series photovoltaic inverters
• Replacement of faulty DC filter boards
• Restoration of DC bus stability
• Industrial photovoltaic inverter maintenance
• Refurbishment of power conversion systems
• Troubleshooting EMI and DC-side filtering issues

💡 Advantages of the Original OMRON Board

✔ Direct compatibility with OMRON KP Series inverters
✔ Effective EMI and high-frequency noise suppression
✔ Improved inverter reliability and stability
✔ Reduced electrical stress on power components
✔ Enhanced energy conversion quality
✔ Extended inverter service life

🔄 Compatibility

Compatible with:

• OMRON KP100L
• OMRON KP125L
• OMRON KP150L

Always verify the board part number (1178253-6C) and hardware revision before replacement.

🟢 Summary

The OMRON PWB (DCF) 1178253-6C DC Filter Board is an essential filtering and protection module used in OMRON KP100L, KP125L, and KP150L photovoltaic inverters. Equipped with high-current inductors, suppression capacitors, and EMI filtering components, it stabilizes the DC bus, reduces electrical noise, protects sensitive electronics, and ensures reliable operation of the inverter's power conversion system.