A Change in Power Strategy Reduces Time to Market
Nord-Electrotechnic was in difficulty. A subsidiary of an American Multinational, it made measurement and positioning equipment, which was sold world-wide via catalogues and distribution channels. Chief Engineer Serge Blanc sighed as he put down the phone, after another call from the Materials Manager Pierre Noir.
Pierre Noir had finished with "… after waiting 20 weeks for delivery we got 10% failures on the last delivery that was 3 units short. And we are still getting 4 to 5% field failures. We have to do something. I want out of this supply by next quarter."
It had seemed like a good idea when designing the Sigma Series to contract with XXX Power for that power supply. After all, providing 5V at 10 Amps, 3.3V at 7 Amps, 24 V at 18 Amps, with a +12V rail at 7 Amps surely wasn't that difficult. Of course finding a vendor that could do it for 500 pieces a year wasn't that easy at a reasonable NRE. And nothing standard from the major players seemed to fit.
Now he also had 2 new designs coming up, with different requirements, and a new 48V motor they wanted to use for higher torque for the Sigma plus…. and here the volumes are only 100 pieces a year.
What to do?
It was clear the existing vendor had to go, but UL and CE approvals would take months with a new custom design.
Serge reached for his coffee, sat back and thought. He remembered the pitch by Jean-Claude Menard, from BM Energie who had called him 3 months earlier, about a product. What was it? He reached for the computer and started on the internet…..
The Solution
Problem Analysis
Serge is faced with a classic engineering problem. He has to provide a reliable supply, which meets his technical requirements at low volume, which are not satisfied by standard products. On the other hand, he needs a power solution that can support the company drive to reduce manufacturing lead times and increase the flexibility you need when supplying 500 plus end products into distribution. International approvals are mandatory. From an Engineering Department perspective, finding a standard solution that would fit all power supply requirements that doesn't need to be relearned on each application would be a real plus in helping with future engineering programs and reducing time to market.
Following a meeting with BM Energie, a distributor for Excelsys, Serge opted for a solution based on a configurable power supply.
He chose the 3gen series from Excelsys and configured a 3G4C1124K128A to meet his requirement.
It had several advantages:
- Excelsys could ship units for qualification, configured with exact set point requirements within 48 hours of receiving an order.
- UL and CE was standard and the reports were available. Radiated and conducted emissions were both below level B.
- The modular approach allows other requirements to be met for volts and amps easily and quickly, without risk - which would really help on future programs
- The Excelsys 48 hour ship program meant that spares could be available quickly if needed.
Program Implementation
A sample was ordered and shipped from the Excelsys plant in Dublin 48 hours later. Using the Excelsys configuration chart the supply was adjusted in the factory for 5.1 volts on output 1, 3.4 volts on output 2 and 25 volts on output 4. Serge felt having a sample this early considerably reduced his risk, as he had a sample to hand immediately for initial engineering qualification and for EMC pre-checking.
Safety documentation was ordered over the Internet and delivered 3 days later enabling the safety process to begin.
In house, chassis modifications were undertaken (it was handy to be able to download the outline drawings from the Excelsys web site), and links were specified to reduce the wiring loom complexity. As an additional bonus these could be specified to be fitted at the factory and the part number was upgraded to a 3G4C1124K128B
The new part number was confirmed in 24 hours and the initial 20 units for the pre-production run ordered and delivery promised within 2 weeks.
A production forecast was placed with BM Energie for Excelsys production planning, and 40 units ordered 1 week after receipt of pre-production units. Units are now ordered on a 4-week lead-time against forecast.
Results
Two programs will now use the 3gen series: this supports the reduction in time-to-market and vendor reduction program and helps increase flexibility.
BM Energie and Excelsys are now a long term partner supporting the strategic goals of the Nord-Electrotechnic.
Cutting Costs for Textile Machinery Manufacturers
using Pulse Power Technology from Excelsys
Problem
A manufacturer of electronic Jacquards approached Excelsys to provide a new power source to drive up to 2,000 switching solenoids used in the control of a cloth weaving process. The existing power system was constructed with linear technology, and was therefore large, heavy, required manual configuration for different worldwide voltages and was expensive to ship. A more efficient, smaller power supply solution was sought.
Problem Analysis
The switching solenoid bank consisted of 2,000 24V(nominal) solenoids, switching at approximately 10 times per second, with each solenoid activated for 33% of the time. Each solenoid required a steady state current of 0.2 Amps. The configuration required a power supply of 24V at 400Amps (almost 10kW peak), operating at 33% duty cycle for an average power of 3.2kW, causing significant heat dissipation in the solenoids, and in turn requiring fan cooling to dissipate the heat.
The existing power supply (an unregulated 50Hz based transformer/rectifier design) was designed to deliver 3.2kW to the load, and required manual transformer tapping for varying worldwide voltages.
The solenoids are rated at a nominal 24V, and require fast pull-in for reliable running of the machine. Analysis of the solenoid operation showed that after an initial pull-in energy requirement, for the remainder of the cycle the solenoid needed less energy for "hold-in". In fact, continued application of power at 24V only serves to cause excess power dissipation in the solenoids, and requires excessive power processing from the power supply.
Solution - Pulse Power Technology
Experimentation showed that reduction of the applied voltage to 12Volt, after an initial pull-in pulse of 10mS, delivered significant energy savings. Through design of a pulsing power supply solution with an output as shown in Fig. 1, significant energy savings became possible.
Benefits of the Solution
As the power dissipated in the solenoids varies as the square of the voltage (Power = V2 / R), the power supply average rating and the power dissipation in the solenoids are both significantly reduced. Importantly, it became possible to remove the troublesome cooling fans and to achieve substantial (up to 70%) cost savings in energy and peak tariff demand.
The new system design decreased shipping weight by 70kgs, and had a volumetric reduction of 65%. Further, appropriate use of switched-mode technology allowed for the provision of a wide range input capability, removing the need to alter taps onsite as part of the installation process.
Cost Justification
The reduced hold-in voltage of 12V allows for up to 75% reduction in hold-in power in the above application. In real life applications, power savings of nearly 65% have been demonstrated.
Consider the above system operating for 20 hours per day, 5 days per week, 50 weeks a year.
Energy Usage using Existing System
3,200W x 20Hr x 5 x 50 = 16,000 kWHr
Energy Usage using Pulse Technology
960W x 20Hr x 5 x 50 = 4,800 kWHr
Energy Savings per year per machine using Pulse Technology
11,200kWHr @ $0.10 per kWHr = $1,120
For the typical application outlined here, the payback period in energy savings alone can be less than one year and there is also a potential for further savings due to a reduction in peak power demand. For example, in a site with 100 machines, the peak power demand is reduced from 320kW to 96kW, resulting in a major reduction in peak demand tariff. In Ireland, for example, this could reduce the annual operating bill by $25,000 per annum through tariff reduction, and this when added to the energy cost saving could result in total savings of around $135,000 annually.
Significant reduction in solenoid power loss also results leading to reduced operating temperatures and increased system MTBF.
