Essential Tips For The Series Mode Of Dual DC Stabilized Power Supply
20 Nov 2025
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Series Mode: Expansion Solution for High-Voltage Output
1. Core Definition & Application Scenarios
In series mode, the output terminals of the two power supplies are connected in a specific way, making the total output voltage equal to the sum of the two channels (U_total = U1 + U2). The current is determined by the channel with the lower rated current (I_total = min(I1, I2)). It is suitable for scenarios requiring high voltage when a single channel is insufficient.
Typical application scenarios:
- High-Voltage Component Testing: Test a 48V-rated LED driver module (single channel max output 30V) by connecting two power supplies in series (30V + 30V = 60V) to meet the test voltage requirement.
- Industrial Equipment Power Supply: Power a 50V-rated small DC motor (single channel outputs 24V) by connecting two channels in series (24V + 24V = 48V), then use the fine-tuning knob to supplement to 50V.
- Laboratory High-Voltage Experiments: Generate a 60V electric field for physics experiments by connecting two 30V/5A power supplies in series, which meets voltage needs while ensuring sufficient current for stable experiments.
2. Switching Operation & Wiring Standards (Key Points)
- Mode Switching: First, turn the voltage and current knobs of both channels to minimum (0V, 0A), turn off the output switch (OUTPUT button popped up), and press the "MODE" button to switch to "SERIES" mode (some power supplies display "串联"). After switching, confirm the panel shows the "SERIES" indicator and that the current displays of the two channels are synchronized (current is controlled uniformly in series mode).
- Correct Wiring Standards (Must Follow):
- Cross-connect terminals: Use a thick wire to connect the "-" terminal of CH1 to the "+" terminal of CH2 (core of series connection to form a voltage superposition loop). The wire must match the single-channel rated current (e.g., 1mm² copper wire for 5A single channel) and be connected firmly to avoid loose contact.
- Load connection: Connect the load’s positive terminal to CH1’s "+" terminal and the load’s negative terminal to CH2’s "-" terminal to form a complete series loop. For example, two 30V power supplies in series: CH1 "-" connected to CH2 "+", load positive to CH1 "+", load negative to CH2 "-"—total output voltage range is 0-60V.
- Common terminal setup: After series connection, CH2’s "+" terminal becomes the common terminal of the two channels. If grounding is needed, connect the common terminal to a dedicated ground post for safety.
- Forbidden Wrong Wiring: Do not connect "+" to "+" or "-" to "-" (parallel wiring mistakenly used for series), as this will cause internal short circuits of the two power supplies, burning power tubes and fuses.
3. Precautions & Safety Protection
- Power Supply Specification Matching: Only connect power supplies of the same model and rated parameters in series (e.g., two KUAIQU SPS-C305S 30V/5A). Series connection of different specifications (e.g., 30V/5A and 24V/10A) will limit current (to 5A only) and easily cause voltage imbalance due to mismatched parameters, triggering protection mechanisms.
- Voltage Upper Limit Control: The total series voltage must not exceed the power supply’s specified series upper limit (most support two-channel series; some high-end models support multi-channel series). Leave a safety margin (total voltage ≤ 1.2x the load’s rated voltage) to avoid load damage from overvoltage.
- Safety Protection Measures: Series connection results in high output voltage (usually exceeding the 36V safe voltage). Wear insulated gloves and shoes, use insulated screwdrivers for wiring, and avoid direct contact with output terminals. After wiring, adjust the voltage to 10% of the target value first; confirm no load abnormalities, then gradually increase to the target value to prevent load damage from sudden high-voltage impact.
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