Understanding Power Consumption in Electronic Locks: Choosing the Right Power Supply Unit (PSU)

Why the Right PSU Matters

Ensuring Reliability

Different electronic locks have varying power consumption needs. Specifying a PSU that doesn't match these needs can lead to system unreliability or even complete failure. For instance, if a PSU is rated to output 1 amp (A) and the locks require 1.5A, the system will lack sufficient power to operate correctly. This mismatch can cause the locks to malfunction, leading to security breaches and operational downtime.

Avoiding Over-Specification

While under-specifying the PSU can lead to failures, over-specifying it can also be problematic. An over-specified PSU can increase costs unnecessarily and lead to higher power consumption, which goes against sustainable practices and contribute to unnecessary energy waste, undermining green initiatives.

Common Voltages in Electronic Locks

Electronic locks typically operate on one of three different voltages:

• 12V DC: This is the most common voltage used in the security industry for electronic locks.
• 24V DC: This voltage is fairly common in applications such as fire systems and vending machines.
• 5V DC: Rarely used, most systems running on batteries utilise 5V DC.

For context, household outlets supply 240V AC in the UK and 110V AC in the USA. 

Power Consumption of Different Locks

Nominal vs. Peak Current

Current: is the rate at which electric charge flows past a point in a circuit. It's essential to distinguish between nominal current and peak current.
 
Nominal Current: This is the standard operating current of the lock.
Peak Current: This is the highest current draw, which occurs during specific operations such as locking or unlocking.
 
Locks fall into specific categories:

High Power Consumption: Solenoids and Electro-Magnets

Solenoids and electro-magnetic fail-unlocked locks are among the highest power consumers. They require a substantial amount of power to operate effectively. For example, a solenoid bolt may draw up to 1.5A at peak current but typically operates at around 200 milliamperes (mA) nominally.
 
For example, a shear magnet or solenoid bolt may have a high peak current draw of up to 1.5A when locking, but their nominal current draw drops significantly to around 200mA.

Low Power Consumption: Motor-Driven Locks

Motor-driven fail-locked locks, on the other hand, are much more power-efficient. These locks typically draw about 150mA nominally and can peak at around 250mA under full load. Their efficiency makes them a preferable choice in many applications, especially where power conservation is a priority.

Calculating power requirements

To calculate the power consumption of electric locks, it is necessary to consider the voltage the lock operates at and the current it draws. The formula for calculating power is:​
 
Power (Watts) = Voltage (Volts) × Current (Amps)​
 
Here's how you can work out the power consumption of electric locks:​

1. Determine the Voltage: Find out the voltage at which the electric lock operates. This information is usually provided in the lock's specifications or user manual.​
2. Measure the Current: You'll need to measure the current the lock draws while in operation. This can be done using a multimeter in current measuring mode. Connect the multimeter in series with the lock's power supply to measure the current flowing through it.​
3. Calculate Power Consumption: Once you have both the voltage and current values, plug them into the formula:​
4. Power (Watts) = Voltage (Volts) × Current (Amps)​

This will give you the power consumption of the electric lock in watts.

Camlock Systems electronic lock examples:

So, what does this mean?​
 
If we were using 10 locks from one PSU, then we need to multiply the peak current by 10​, and then add 10% for variance: -​
 
250mA x 10 = 2500mA (2.5Amps)+ 10% = 2750mA (2.75Amps)….so a 3-amp PSU would be specified

Conclusion

In summary, choosing the right PSU for electronic locks is critical for maintaining system reliability and efficiency. Understanding the power requirements of different locks, including their voltage and current needs, ensures that the PSU is neither under-specified nor over-specified. This balance is essential for cost-effectiveness and sustainability, particularly in competitive and environmentally conscious markets.
 
By carefully considering these factors, you can select a PSU that supports the optimal performance of electronic locks, ensuring security and efficiency in operations.