TOMZN TOM7Z 2P DC 1000V Solar Molded Case Circuit Breaker (MCCB)

1. Introduction

The TOMZN TOM7Z series DC Molded Case Circuit Breaker (MCCB) is designed to provide reliable overload and short-circuit protection for DC power systems, particularly in solar photovoltaic (PV) applications. This manual provides essential information for the safe and effective installation, operation, and maintenance of your MCCB.

Figure 1: TOMZN DC MCCB (125A and 160A models shown)

2. Safety Information

Please read and understand all safety warnings and instructions before installing or operating this device. Failure to follow these instructions may result in electric shock, fire, or serious injury.

• Installation and maintenance should only be performed by qualified personnel.
• Always disconnect power before working on the circuit breaker or connected equipment.
• Ensure proper grounding and wiring according to local electrical codes and standards.
• Do not operate the circuit breaker if it is damaged or appears to be malfunctioning.
• The device is designed for DC applications up to 1000V. Do not use in AC circuits or exceeding specified voltage/current ratings.
• Ensure terminals are securely tightened to prevent loose connections and overheating.

3. Product Features

• Overload Protection: Safeguards circuits from excessive current.
• Short-Circuit Protection: Provides rapid disconnection in case of a short circuit (0.1 second response time).
• High-Quality Contacts: Designed for high conductivity and efficient current carrying.
• Large Handle Design: Features a high-hardness operating handle, resistant to compression and wear, with safety insulation.
• Double Insulation: Insulated internal structure for enhanced safety and ease of installation.
• Reliable Arc Extinguishing: Optimized design with a large volume arc extinguishing chamber for reliable fault current breaking.
• Flame Retardant Material: Constructed from materials that resist flame propagation.

Figure 2: Instant Disconnect for Overload/Short-Circuit Protection

Figure 3: Key Advantages of the MCCB

4. Installation and Setup

The TOMZN TOM7Z MCCB is designed for easy installation. Follow these steps carefully:

4.1 Component Identification

Figure 4: Circuit Breaker Components

• Trademark: TOMZN brand logo.
• Handle Switch: Used to manually turn the circuit breaker ON or OFF, and indicates trip status.
• Parameter Information: Displays model, rated current (In), rated voltage (Ue), insulation voltage (Ui), impulse withstand voltage (Uimp), ultimate short-circuit breaking capacity (Icu), service short-circuit breaking capacity (Ics), and operating temperature category.
• Test Button: Used to manually test the tripping mechanism.

4.2 Wiring Instructions

Ensure all connections are secure and correctly polarized. The MCCB is a 2-pole device for DC circuits.

Figure 5: Terminal Connections (Positive and Negative)

1. Identify the positive (+) and negative (-) terminals on the MCCB.
2. Connect the incoming DC positive (+) wire to the designated positive terminal on the MCCB.
3. Connect the incoming DC negative (-) wire to the designated negative terminal on the MCCB.
4. Connect the outgoing DC positive (+) wire to your load (e.g., inverter, charger, battery bank) from the corresponding positive terminal on the MCCB.
5. Connect the outgoing DC negative (-) wire to your load from the corresponding negative terminal on the MCCB.
6. Ensure all terminal screws are tightened to the recommended torque to prevent loose connections and potential hazards.

4.3 Typical Wiring Diagrams for Solar PV Systems

Below are common wiring configurations for solar photovoltaic systems:

Figure 6: Wiring Diagram: Battery to MCCB to Load (Inverters/Chargers)

This diagram illustrates connecting a DC power source (e.g., battery bank, DC12-400V) through the MCCB to a DC load such as inverters or chargers. The MCCB provides protection for the load circuit.

Figure 7: Wiring Diagram: Solar Panels to MCCB to Batteries

This diagram shows the MCCB installed between solar panels and a battery bank. In this setup, the MCCB protects the battery bank and the charging circuit from overcurrents originating from the solar array.

5. Operation

• Turning ON: Push the handle switch upwards to the 'ON' position.
• Turning OFF: Push the handle switch downwards to the 'OFF' position.
• Tripping: In case of an overload or short circuit, the handle switch will automatically move to a central 'TRIP' position (or 'OFF' depending on the model) to disconnect the circuit.
• Resetting after a Trip: If the circuit breaker trips, first identify and resolve the cause of the overload or short circuit. Then, fully push the handle switch to the 'OFF' position before pushing it back to 'ON' to reset.
• Test Button: Periodically press the 'PUSH TO TRIP' button to ensure the tripping mechanism is functional. The breaker should trip immediately. Reset it after testing.

6. Maintenance

• Regular Inspection: Periodically inspect the circuit breaker for any signs of physical damage, discoloration, or loose connections.
• Cleaning: Keep the circuit breaker clean and free from dust and debris. Use a dry, soft cloth for cleaning. Do not use liquid cleaners.
• Terminal Check: Ensure all terminal connections remain tight. Re-tighten if necessary, especially after initial installation and during routine maintenance checks.
• Environmental Conditions: Ensure the operating environment remains within the specified temperature range (-5°C to +40°C) and is free from excessive moisture or corrosive gases.

7. Troubleshooting

• Circuit Breaker Trips Frequently:
  • Cause: Overload or short circuit in the protected circuit.
  • Solution: Disconnect all loads and reset the breaker. Reconnect loads one by one to identify the faulty device or circuit. Check for damaged wiring or faulty components.
• Circuit Breaker Does Not Reset:
  • Cause: Persistent fault (overload/short circuit) or internal damage to the breaker.
  • Solution: Ensure the fault is cleared. If it still doesn't reset, the breaker might be damaged and needs replacement.
• Overheating at Terminals:
  • Cause: Loose connections or undersized wiring.
  • Solution: Disconnect power, check and tighten all terminal screws. Ensure wire gauges are appropriate for the current rating.

8. Specifications

The following table details the technical specifications for the TOMZN TOM7Z series DC MCCB:

Figure 8: Approximate Dimensions for Different Current Ratings

9. User Tips

• Matching Current: Always select an MCCB with a rated current appropriate for your specific solar PV system and connected loads to ensure optimal protection.
• Clearance: Ensure adequate clearance around the MCCB for proper heat dissipation and ease of access for operation and maintenance.
• Professional Installation: For complex solar installations, it is highly recommended to consult with a certified electrician or solar professional.

10. Warranty and Support

For warranty information, technical support, or service inquiries, please contact your retailer or the manufacturer directly. Keep your purchase receipt as proof of purchase.