Danfoss Electronic Unit for BD35/50F Compressors

General Information

The electronic unit is a dual voltage device, compatible with both 12V and 24V power supply systems. It supports a maximum voltage of 17V for 12V systems and 31.5V for 24V systems. The maximum ambient temperature is 55°C. The unit features built-in thermal protection that stops compressor operation if the unit's temperature becomes too high.

Installation

Connection to Compressor: Connect the terminal plug from the electronic unit to the compressor terminal. Mount the electronic unit on the compressor by snapping the cover over the screw head (1).

Power Supply: The electronic unit must be connected directly to the battery poles (2). Ensure correct polarity (+ to + and - to -) for proper operation. The unit is protected against reverse battery connection.

Fuse and Main Switch: A fuse (3) is recommended in the + cable, as close to the battery as possible. A 15A fuse for 12V circuits and a 7.5A fuse for 24V circuits are recommended. If a main switch (4) is used, it should be rated for a minimum current of 20A. Observe wire dimensions as per Figure 2. Avoid extra junctions in the power supply system to prevent voltage drop affecting battery protection settings.

Battery Protection: The compressor stops and restarts according to designated voltage limits measured on the + and - terminals of the electronic unit. Standard settings for 12V and 24V power supply systems are shown in Figure 3. Optional settings (Figure 4) are available if a connection with a resistor (9) is established between terminals C and P. For solar applications without a battery, a 220 kΩ resistor is recommended. In AEO (Adaptive Energy Optimizing) speed mode, the BD compressor adjusts its speed to the cooling demand within a random operation voltage of 9.6 to 31.5V.

Thermostat Connection

The thermostat (7) connects between terminals C and T. Without a resistor in the control circuit, the 101N0210, 101N0220, or 101N0240 models run at a fixed speed of 2,000 rpm when the thermostat is switched on. With the thermostat directly connected to terminal C, the 101N0300 or 101N0320 models adjust speed to the cooling demand. Fixed compressor speeds between 2,000 and 3,500 rpm can be achieved by installing a resistor (8) to adjust the control circuit current. Refer to Figure 5 for resistor values for various motor speeds.

Fan Operation

An optional fan (5) can be connected between terminals + and F. Connect the plus to + and the minus to F. The output voltage between terminals + and F is regulated to 12V, so a 12V fan must be used for both 12V and 24V power supply systems. The fan output can supply a continuous current of 0.5A avg. A higher current draw is allowed for 2 seconds during start.

LED Error Indications

A 10mA light emitting diode (LED) (6) can be connected between terminals + and D. The LED flashes to indicate operational errors. The number of flashes corresponds to the error type. Each flash lasts 1.5 seconds, followed by a delay, repeating the sequence every 4 seconds.

• 5 flashes: Thermal cut-out of electronic unit (unit overheated due to heavy load or high ambient temperature).
• 4 flashes: Minimum motor speed error (motor cannot maintain minimum speed of 1,850 rpm due to heavy load).
• 3 flashes: Motor start error (rotor blocked or high differential pressure >5 bar).
• 2 flashes: Fan over-current cut-out (fan load exceeds 1A peak).
• 1 flash: Battery protection cut-out (voltage outside cut-out setting).

VDE/UL Approvals for BD Compressors

The following tables show approved compressor and electronic unit combinations for VDE/UL certifications.

Approved Compressor - Electronic Unit Combinations

Electronic Unit Combinations

Legend:

• = Combination possible, VDE or UL approval
• = Combination possible, but no approval
• = Combination not possible