Electricity and Control November 2024

PLANT MAINTENANCE, TEST + MEASUREMENT

Simplifying battery management for dual voltage systems Power supplies to support remote monitoring stations are often limited in field environments. Most of the telemetry industry uses 24 V or 12 V systems, and this can be a challenge when designing battery backup systems.When instrumentation and radio communication devices run on different voltage supplies, having technology that can adapt to the different voltage requirements is convenient and cost-effective. Here, Ian Loudon, International Marketing and Sales Manager at remote monitoring specialist Omniflex, outlines the advantages of dual voltage power supply.

T elemetry equipment is often used in the field to relay information back to control systems, but one of the big challenges is that there is often a disparity between radio and instrumenta tion equipment power supply voltages. Providing both 24 V and 12 V in battery standby systems can be expensive and inconvenient. Radio equipment is often powered on 12 V dc supply – the most readily available batteries. However, analytical equipment, control relays and others often require 24 V dc power. Traditionally, companies have used two power supplies to address this issue. This increases complexity, with more wiring and more maintenance time, typically involving twice the cost in cabling and requiring twice the amount of time for checking on any signals. The traditional approach would also require two power supply chargers and batteries for remote monitor ing, adding more components to the system. In addition, the draw on the 12 V dc system is different to that on the 24 V dc system, which means the batteries drain at different rates and that raises another maintenance challenge. Many maintenance teams would carry backup batter ies with them, but the most common backup battery is the sealed lead acid battery, because it is relatively cheap and readily available. In high ambient temperature conditions, however, a charger, operating even at trickle charge, will damage the batteries and shorten their lifespan. All sealed lead acid battery manufacturers specify a maximum charg ing current for the correct life and safe operation of sealed lead acid batteries. The PTL120C-D takes battery protec tion to a new level by providing a temperature sensor input – where the sensor is attached to the battery – which allows the charge controller to compensate the charging rate ac cording to the temperature of the battery. This extends the battery life significantly. The maximum charging current for a battery is based on the Ampere-hour capacity of the battery. A further consideration is that many conventional switch mode power supplies do not control their maximum deliv ered current and can cause batteries to be charged from flat with current levels that exceed the manufacturer’s rec ommendation.

In addition, during prolonged power outages, back up batteries will eventually discharge. If the load remains connected, the batteries can enter their ‘deep’ discharge phase, which can cause irreparable damage to the batter ies, and reduce their capacity and life expectancy. To simplify the challenges of power supply and back up for remote monitoring, Omniflex has developed a single product solution in the PTL120C-D dual voltage charger – with both 12 V and 24 V dc output. It provides true split rail battery charging for balanced charging to both batteries, even when 12 V loads are tapped from the battery set. This protects the batteries from deep discharge events as it contains mains output that is connected as an alarm to indicate loss of primary power – notifying a supervisory system. The battery level is monitored through the charger and the load can be set to prevent damage. Furthermore, an alert will signal that a specialist is needed to fix the prob lem. With a simplified design in a compact, single unit solu tion, the PTL120C-D dual voltage charger makes main tenance easier and flexible, avoiding the need to involve certified wiremen to change power supply through a mains safe IEC connector. □ Omniflex developed the PTL120C-D dual voltage charger – with 12 V and 24 V dc output – to simplify the challenges of maintaining power supply and backup for remote monitoring stations.

For more information visit: www.omniflex.com

NOVEMBER 2024 Electricity + Control

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