How to Implement Multi-Pump Constant Pressure Control via M720 System Wiring & Configuration

Implementing multi-pump constant pressure control with the M720 system mainly involves hardware communication wiring, sensor installation, and specific parameter configuration for master and slave (auxiliary) drives.

1. Hardware Wiring

1.1 Communication Connection

• The multi-pump system is connected via RS485 communication cables.
• Wiring method: Parallel connection – connect the S+ terminals of all drives together, and the S- terminals together.
• M720 supports "Dual Master + Multi-Slave Online" mode, which can control up to 1 master drive + 4 auxiliary drives (or 2 master drives + 3 auxiliary drives).

1.2 Sensor Installation

• The Master Drive must be equipped with a pressure sensor to detect pipe network pressure and send signals to slave drives.
• If a Standby Master Drive is configured, it must also be connected to a pressure sensor to automatically take over the system when the main master drive fails.
• Ordinary slave (auxiliary) drives usually do not require sensor installation.

1.3 Power & Motor Wiring

• Power input is connected to R, S, T terminals, and motor output is connected to U, V, W terminals.

2. Pressure & Basic Parameter Settings

2.1 Target Pressure Setting

• When the master drive is stopped or running, press the "+" or "-" key on the panel for 3 seconds to directly set the target pressure (Parameter U0-00).

2.2 Sensor Type & Range

• On inverters connected with sensors (master and standby master), set U0-03 (Sensor feedback type, e.g., 4-20mA corresponds to 1) and U0-04 (Sensor range, e.g., 10.0 Bar).

2.3 Rotation Direction Confirmation

• Adjust the motor rotation direction via U0-02 (0 = Forward rotation, 1 = Reverse rotation), or swap any two of the motor output wires U/V/W.

3. Multi-Pump Linkage Parameter Configuration

Configure according to the number and role of pumps in the system:

3.1 Master Drive 1 Configuration

• Local Address (U3-01): Set to 1.
• Number of Auxiliary Drives (U3-03): Set according to the actual number of slave drives (e.g., set to 2 for a 3-pump system).
• Pump Rotation Time (U3-02): Set the alternate running time of each pump, default is usually 480 minutes (8 hours).

3.2 Standby Master Drive Configuration (if applicable)

• Local Address (U3-01): Set to 2.
• Start/Stop Command Selection (U0-10): Set to 2 (Communication control start/stop).
• Frequency Reference (U0-13): Set to 2 (Communication reference/Slave communication 2).

3.3 Slave/Auxiliary Drives Configuration

• Local Address (U3-01): Set to 3, 4, 5 in sequence.
• Start/Stop Command Selection (U0-10): Set to 2 (Communication control).
• Frequency Reference (U0-13): Set to 2 (Communication reference).

4. Core Linkage Logic Explanation