DC Power Systems are the critical first step in designing an effective Automation system. We often overlook this crucial step, so our Automation & Control Experts share the considerations below to help guide you. Taken from our Tech Talks series, our goal is to help ensure that you have thought through all important factors in selecting the proper DC Power System. To learn more about our Tech Talks series, click here.
- Health, safety, or environmental impacts?
- Economic Consequence of failure?
a. Hazardous Area
- None = general purpose
- NEC 500 Class 1
- ATEX Zone 2
- IEC Ex Zone 2
b. Enclosure Requirements
- Maximum temperature
- Minimum temperature
- Space constraints (height, width, and depth)
- Remote accessible for troubleshooting and configuration?
- Siemens TIA compatible (Leveraging PLC function blocks and HMI faceplates for system for status, diagnosis, control, and troubleshooting.)
- Output Voltage:
- Output Current:
- Input voltage range and frequency (e.g. 85V to 550V AC at 50/60 Hz)
- Efficiency requirement? (e.g. >= 90% efficiency)
- Power boost requirements?
- Relay fault contact?
- Adjustable output voltage?
- Number of independent isolated loads/feeds?
- Load per circuit?
- Local indication needed?
- Remote indication per circuit trip and remote reset capable?
- Control needed – ability to de-energize and re-energize each circuit?
- # of seconds, minutes, hours, days
- Percent of normal load
- Plus UPS charging load
- Capacitor-based UPS
- When the application fits, capacitor-based systems should be selected over batteries. Capacitors last significantly longer than batteries, they have a wider temperature range, they charge faster, they do not emit a hazardous gas and therefore don’t require encloser venting. There is less maintenance on a capacitor-based system over a battery-based DC buffering system. If your system requires less that 15 amps of DC buffering for a buffering time measured in seconds to minutes, the UPS500S is a great solution. For applications needing up to 40 amps of DC buffering time measured in minutes to hours, the UPS1600 with external battery modules is the right solution.
- The Siemens capacitive based UPS500S has a 15-amp total load capacity. Buffer time at 15 amps is 9 seconds to 40 seconds. Buffering time with a 1-amp load is 138 seconds to 572 seconds. Additional buffering modules are required to achieve greater DC buffering times. Refer to KT10.1 SITOP catalog (www.awc-inc.com) for the buffering time chart bases on load and the number of buffering modules.
- Quantity of redundant power supplies
- Load balancing required
- Excess of 20 amps of redundancy required
- Yes – 2 redundancy modules are required.
- No single point of failure required
- Yes – 2 redundancy modules are required.
a. SIL 3 (i.e. HIPPS)
- System needs to withstand 3 faults while maintaining power to the DC bus and supply DC power to the critical output devices.
- Wide range AC input supply voltage of 85V to 550V AC. The widest range on the market that will work in all areas of the world and require less models to
carry, supply, and support.
- Wide temperature range of -25 deg C to +70 deg C and an extremely slim design with no lateral installation clearance requirements. Can use these DC
power systems in the heat of Saudi Arabia and the cold of Northern Canada without additional panel heating or cooling. Can place these power supplies
side by side on a standard din rail saving rail space for more items.
- Triple hazardous area rating of UL Class 1 Division 2, ATEX zone 2, and IEC Ex zone 2. Can place all over the world with less models to carry,
supply, and support.
- Adjustable potentiometer for DC voltage adjustment of 24V to 28.8V. Voltage adjustment to offset voltage drops on long cable runs or when multiple
devices are powered off the same circuit.
- Power boost feature allows 3 X the rated current (for 25ms) for tripping protective devices downstream of the power supply. Fast overload conditions do
not trip the power supplies internal circuit breaker causing loss of the DC power before tripping the intended circuit breaker or fuse downstream. 1.5
times rated current (5 s/min) to address starting inrush currents.
- Normally open “DC OK” relay contact block which can be tied back to the control system for remote DC power indication.
- The Modular series is 94% efficient, the highest in the industry reduces energy loss and heat impacts.
- 5A, 10A, 20A, and 40A models work in 50Hz and 60HZ systems, single phase, dual phase, and three phase AC supply applications.
- AWC extensive stock and competitive pricing.