Recommended Voltage Settings for BLVD and LLVD

The primary and secondary power-off settings in base station DC power supply systems are mainly distinguished based on differences in battery discharge voltage. When the utility power fails and the base station is powered by the battery pack, the importance of wireless equipment and transmission equipment varies (transmission equipment is typically more critical than wireless equipment). To ensure longer power supply for transmission equipment, the DC output is divided into two sections: primary power-off and secondary power-off. During normal battery discharge, both primary and secondary power-off branches remain operational. However, as the battery capacity decreases and the discharge voltage drops (e.g., the primary power-off voltage is usually set at approximately 45.12V), the power system automatically disconnects the primary power-off branch, and the battery supplies power only to the secondary power-off branch (e.g., critical transmission and monitoring equipment).

Summary and Optimization

1. Differences Between Primary and Secondary Power-Off:
   • Primary Power-Off: Supplies power to less critical loads (e.g., wireless equipment).
   • Secondary Power-Off: Supplies power to critical loads (e.g., transmission equipment). The secondary power-off design ensures the continuity of transmission links during utility power outages.
2. Purpose of Primary and Secondary Power-Off:
   • During utility power outages, when battery capacity nears depletion, the system disconnects the primary power-off loads to allocate all remaining energy to secondary power-off loads, ensuring the stable operation of transmission equipment.
3. Principle of Secondary Power-Off Function:
   • As the battery discharges, its output voltage gradually decreases. When the voltage drops to a predefined threshold (typically referred to as the cut-off voltage), the load must be disconnected to prevent over-discharge, which could shorten battery life or cause damage. This load disconnection at the cut-off voltage is called low voltage protection.
   • Secondary power-off is an advanced optimization of low voltage protection. When the battery voltage reaches a preset value (usually higher than the cut-off voltage), the system first disconnects non-critical loads, retaining power for critical loads. As the voltage continues to drop to the cut-off voltage, all loads are disconnected to protect the battery. This two-stage load disconnection mechanism is known as secondary power-off.
   • The advantage of secondary power-off is that it extends the runtime of critical equipment while protecting the battery, minimizing communication interruptions.
4. Configuration for Implementing Secondary Power-Off:
   • During system initialization, DC output loads must be divided into primary (critical) and secondary (non-critical) loads and connected to corresponding branches.
   • Advanced power equipment should support flexible secondary power-off settings, allowing users to adjust voltage thresholds for primary and secondary power-off or disable these functions entirely to meet site-specific priority requirements.