BGAs, Blade Servers, Utility Deregulation and Other Challenges for Power Quality in 2008

The Affect on PQ 2008 of: Ball Grid Arrays Blade Servers Power Factor Corrected Power Supplies Utility deregulation: Specifically, the Use of PFC capacitors and the affect of the event on power supplies and components

Well review changes that may affect your budget in Smaller component size, but more heat More power in less rack space Spare parts cost very likely to increase Same footprint but an increase in wattage Changes for the world compliance of power supplies made that affects your facilitys Power Quality Utility changes that saves you money, but at what cost?

Topic #1: What is a Ball Grid Array The Ball Grid Array (BGA) package achieves the objectives of providing increased functionality for the same package size while being compatible with existing Surface Mount Technology (SMT) infrastructure. Varieties in packaging include: Plastic Ball Grid Array (PBGA) TE-PBGA (Thermally Enhanced BGA) EBGA (Enhanced BGA) TSBGA (Tape Super BGA)

Benefits of using BGA packages over similar lead count packages include: Efficient use of board space. Improved thermal and electrical performance. BGAs can offer power and ground planes for low inductances and controlled impedance traces for signals. Improved surface mount yields compared to similar fine pitch leaded packages. Reduced package thickness.

BGA vs. conventional Quad Flat Packs (QFPs) 1.5 mm pitch spheres (bottom side of a PBGAS225) BGAs are less fragile and easier to handle. A 160-lead 0.3 mm (11.8 mil) pitch QFP

BGAs

Things to watch out for in BGAs Higher inrush and more power in smaller sizes No more repairing boards yourself (without x- ray inspection equipment) Prepare for higher replacement (Spare) parts in the future Prepare for delays in availability or repair of the boards – change philosophy to consider keeping parts on-site.

Blade Servers & UPS More power consumption in less space Same rack space so the UPS must be still good! n+1 power supplies (P/S) often the same but they are more utilized Many companies plan on changing the UPS and P/S in the future but do they ever get around to it?

Blade Servers 10 slots with dual processors 20 times the processing power in the same rack space (7U) 20 times the heat and 20 times the power required (200 Watts vs. 4,000 Watts)

Topic # 2: Blade Servers 10 times the amount of servers in the same 7U rack space! That means a lot more power in standard 42U rack More power and more heat – same rack and room size More heat = more trouble

Things to watch out for in Blade Servers Overheating the room – Hot spots High temperature usually brings low humidity (and increased static issues) Internal power supplies run hotter which increases the heat output Change in power requirements means the old UPS may be undersized or the back up time is severely compromised

Topic #3: PFC Corrected Power Supplies affect on PQ in 2008 Because a switch-mode power supply, like one found in any computer's power supply, conducts current in small pulses, it has waveforms that are in phase, but the current waveform is not sinusoidal. This is not good for the power factor either and this is why the load is called non-linear. A non-linear load has a non-sinusoidal current waveform. Non-linear loads are probably the loads your utility company hates the most because a non-linear load draws harmonic currents from the AC mains. Luckily, the power factor correction used in power supplies reduces these harmonics. This reduction in harmonics can in turn clean up the power for everything else plugged into this circuit.

What is Power Factor? Power factor is the ratio of real power consumed to apparent power, or Watts over VA. Traditionally, PF is known as the phase difference between the sinusoidal voltage and current (amperage) waveforms. Something that has a "linear load," like a simple resistor, has identical voltage and current waveforms, are sinusoidal and are in phase with each other. Current and voltage in a linear load have both identical sinusoidal waveforms. Some electronics, like motors, have a current waveform that lags behind the waveform for the voltage. The waveforms are still sinusoidal, but they are out of phase. This affects their power factor. These loads are called "inductive." Current and voltage waveforms in inductive loads are sinusoidal, but out of phase.

Active vs. Passive PFC Power Supplies Note the large coil in this power supply at the bottom of the photo. This is passive PFC. Passive PFC uses a passive element, such as a large ferrite core, to dampen the harmonics. Unfortunately, power factor using such means can only be corrected to about 80%. A 500 Watt Active PFC circuit board Components such as FET's, diodes and even IC's are used to improve power factor to 95% or better! Active PFC can also automatically adjust the input voltage of a power supply.

Things to watch out for in PFC Corrected Power Supplies In the USA, Watts =VA (part number for a 300W P/S (500 VA) is now a 500 Watt P/S. If an old P/S is switched in an existing system, dont be surprised if the UPS that had powered the system for years, is now simply too small. Worldwide, PFC P/S have lower VA = savings on electric bill. For USA, the PFC power supply is actually less efficient than a non-PFC model, but this penalty tends to only be around 5%.

EN (EN61000) called for PFC Corrected Power Supplies Brings voltage and current back in phase Now Watts = VA P/S manufactures changed part numbers to match replacements that matched the Watts to the old VA. Danger!!!! UPS sized in watts but PFC P/S increased the watts to equal VA so the UPSs could now be undersized.

Topic 4: Utility Deregulation Challenges for PQ in 2008 Lack of long term investments in infrastructure Many Utility companies have changed from a 50 year payback to a 4 year payback Loads are no longer resistive but are mostly electronic. In order to maximize the revenue stream on the existing power lines, Utilities need to add PFC capacitors to bring V&I in phase allowing them to charge the actual rate.

Utilitys PFC Capacitors

Over voltage due to PFC switching Notice how the over voltage causes the load current to increase

Multiple Zero-crossings due to PFC switching The multiple zero crossing causes a severe di/dt change in current and is very high in amplitude

PFC causes a 4-6 mSec. event low voltage with a frequency of 3-5 kHz. Over voltages Multiple zero-crossings Low frequency ringing in surge suppressors causes and actual gain in amplitude Demand controlled or timer controlled Degrades UL/CE/FCC filters and suppressors Ground current leaks during operation Premature failure

PFC affect on AC/DC power supplies The over voltages damages FCC, UL/CE filters – causing leakage current to ground Multiple zero crossings causes a Null State of 0 Volts in the rectifier depleting the Cap causing a in-rush of current to the load (laser diodes) and the Cap. I 2 R losses heats up the components – if the reverse biasing does not kill the diode first.

How does the voltage leak to ground? The FCC, UL and CE all require that a Corcom type filter be added to all electronics Over voltage stresses the MOV or caps and cause current to flow to ground

Things to watch out for in Utility Deregulation Less total Ampacity available Adding PFC Capacitors at a faster rate Lower rates (due to lack of penalties) but nothing is free; more power protection may be required High speed electronic equipment fails prematurely or will have system resets

Summary BGAs, Blade Servers all mean more power in smaller space Increase current and heat will increase T&H/Static issues may look like PQ issues Power Factor Corrected P/S could be overloading existing UPSs Utility deregulation means more power protection likely required

PQ tips for 2008 & Beyond Do more baseline PQ monitoring Monitor both voltage and current Monitor ground current and track increases Contact Utility annually – keep updated Monitor T&H (in several places if possible) – determine air flow