News in the Channel - issue #26

DUAL VOLTAGE SYSTEMS

Simplifying battery management for dual voltage systems Power supplies are often limited in field environments as most of the telemetry industry uses 24V or 12V systems, which can be a challenge when designing battery backup systems, but there is technology that can help, as Ian Loudon, international marketing and sales manager at Omniflex, explains.

Providing 24V and 12V in battery standby systems can be expensive and inconvenient. Telemetry equipment is often used in the field to relay information back to control systems, but a big challenge is there can often be disparity between radio and instrumentation equipment power supply voltages. Radio equipment is often powered on 12V DC supply. However, analytical equipment, control relays and others often require 24V DC. Traditionally, companies would use two power supplies to address this issue. This brings complexity with more wiring and maintenance time as this may involve twice the amount of time checking on any signals and twice the cost in cabling. Traditionally this would require two power supply chargers and batteries for remote monitoring, therefore adding more components to the system. In addition, the draw on the 12V DC system is different to the 24V DC system, which drains the batteries at different rates and makes maintaining them a challenge. Many teams would carry back up batteries, but the most common back up battery is sealed lead acid because it’s relatively cheap and readily available. In high ambient temperature conditions, however, a charger will even at trickle charge damage the batteries and shorten their lifespan. All sealed lead acid battery manufacturers specify a maximum charging current for the correct life

and safe operation of sealed lead acid batteries. Many conventional switch mode power supplies do not control their maximum delivered current and can cause batteries to be charged from flat with current levels that exceed the manufacturer’s recommendation. In addition, during prolonged power outages, back-up batteries will eventually discharge. If the load remains connected, batteries can enter their ‘deep’ discharge phase, which can damage to the batteries and reduce their capacity and life expectancy. To simplify the challenges of remote monitoring Omniflex has developed a single product solution featuring a power supply with the PTL120C-D dual voltage charger – with 12V and 24V DC output. It provides split rail battery charging for balanced charging to both batteries even when 12V loads are tapped from the battery set. This protects the batteries from deep discharge events, containing mains output that is connected as an alarm to indicate loss of primary power. The battery level is monitored through the charger and the load can be put to prevent damage, alerting a specialist to fix the problem. With a simplified design through a compact single unit solution, this makes maintenance easier by avoiding needing certified wiremen to change power supply through a mains safe IEC connector.

Ian Loudon International marketing and sales manager

omniflex.com

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Radio equipment is often powered on 12V DC supply. However, analytical equipment, control relays and others often require 24V DC.

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