Case study : Energy efficiency ,benchmarking and  estimation & measurement in case of  Telephone Exchanges

Er Deepak Sathe

(Dip in Elect Engg)

Introduction:

                    Power Usage Effectiveness (PUE) and its reciprocal Data Center infrastructure Efficiency1 (DCIE) are widely adopted standards in case of Data center for determining efficiency of infrastructure , as part of an effective energy management.

                 These standards to determine how much energy efficient data centers / IT industry are, and to monitor the impact of their energy efficiency efforts.

PUE = Total Facility Power / IT Equipment Power

DCiE = IT Equipment Power / Total Facility Power

PUE	DCiE	Level of Efficiency
3.0	33%	Very Inefficient
2.5	40%	Inefficient
2.0	50%	Average
1.5	67%	Efficient
1.2	80%	Very Efficient

Table 1

  Desired PUE   for Data centers is 1.5 or less.

                   The Uptime Institute / Green Grid are such agencies / organization which recognize claims of data centers.

In case of telephone exchanges Monitoring of energy consumption was done regularly with following parameters:

1. Electric unit consumed        ( Unit / Line / Month )

2. Electricity charges               ( Rs. / Line / Month )

3. Penalties in Electricity bills    ( Rupees )

4. Rebate  for maintaining better power factor close to unity.

In   maharashtra  these parameters (1 & 2 )varied in vide range depending upon use of building for different purposes.

               Also Telephone exchanges are considered as “Office Buildings” for Energy conservation for BEE. While computing Energy savings it is just difference of energy consumption for two years. There is no consideration for checking of total energy consumption with reference to equipment load, addition / deletion of equipment load, climatic conditions in respective years.

Benchmarking standards :

                    For telephone exchanges some benchmarking has to be fixed to evaluate their performance based on energy consumption for exchange equipment with reference to total facility energy consumption.

                    We may adopt benchmarking standards on similar pattern as used for Data centres & IT industry in addition to above to monitor the impact of their energy efficiency efforts.

              It is well known fact that For Telephone exchange, Energy consumption pattern is as follows:

1. Telephone exchange equipment                                                     40%

2.  Air conditioning                                                                               50%

3. Other load electrical fittings ,fans, pumps, compound light etc.      10%

                      It can be very well noted that major component in telephone exchanges is Air – conditioning load which is depend upon climatic zone i.e. ambient temperature and vary season to season and also during time of day.

POWER VS ENERGY

The PUE and DCiE  can be computed using either power (kilowatt) or energy (kilowatt-hour) measurements.

Power measurements is single-point efficiency measurement only gives the energy flow at the exact time of measurement while energy measurements accumulate energy flow over time ( day / month / year).

                         Hence considering this aspect we may adopt

                         Power Utilization Effectiveness based on Energy measurement.

                         PUE =     Total facility Energy consumption / Exchange equipment Energy consumption

Estimation & measurement:

Energy use of every power-consuming device in a telephone exchange is to be measured and accounted. However, it can be complex, expensive, and impractical to measure energy use of some devices. In many cases, indirect

measurement and estimation of devices can allow determination of the PUE in a practical and cost-effective manner.

We may adopt basic level (Level 1* “The Green Grid”) for data collection   monthly measurement practice.

To perform Telephone exchange efficiency calculations, it is important to clearly define which power constitutes Exchange ( IT ) load, and which power is physical infrastructure.

We may consider Telephone exchange building / complex consisting of  Exchange ( IT ) load as

Main Telephone exchanges or RSU or small capacity exchanges,

OFC / MW Transmission centers,

PCM rooms,

Mobile switch rooms, BTS,

Data Centers,

                   MDF  etc.

And Power plant   Rectifier SMPS type or UPS with VRLA battery as main primary standby source.

In short ac power fed to UPS OR Rectifier for ac or dc telephone equipment.

And physical  (Electro –mechanical ) infrastructure load as

Transformer substation,

DG set as secondary standby source,

Air-conditioning systems,

Internal Electrical light and fan fittings,

Pumps,

Lifts,

Fire detection system,

Fire fighting system,

Security systems,

External lights gate / compound / neon sign etc.

                    In case of Electronic telephone exchanges load governed by installed capacity is constant irrespective of traffic and number of working lines. We can very well calculate exchange ( IT ) load and its energy consumption measuring current and voltage and power factor. 

                   The Energy meter reading of Supply Company shall be total facility energy consumption.

                   Certain loads such as inspection quarter, recreation club etc may not be considered as part physical infrastructure, there consumption may considered judicially.

Evaluation PUE / DCiE  results:

              PUE and DCiE are excellent for understanding how effective telephone exchange infrastructure is delivering power to its exchange IT equipment. Location and its climate ,orientation, size , use of building, type of equipment, desired environmental conditions for equipment for operation / life point of view and many other factors all play a important role in a data center’s final results.

                 Averaging monthly PUE results for year shall give good information / understanding about performance. It will also give useful insights in to how your data center works short-term or rapid changes to various internal and external conditions.

Depending upon Climate zone “Level of Efficiency” may proposed as follows:

Level of Efficiency	(Average for Year )PUE
	Hot & Dry, Warm & Humid, Composite Climate	Cold,Moderate/Temperate Climate
Very Inefficient	More than 3.3	More than 2.8
Inefficient	2.8 to 3.3	2.3 to 2.8
Average	2.3 to 2.8	1.8 to 2.3
Efficient	1.8 to 2.3	1.3 to 1.8
Very Efficient	Less than 1.8	Less than 1.3

Table 2

Conclusion:

This case study defines an approach to evaluate power / energy consumption in Telephone Exchanges with reference to an effective energy management and showing how to calculate PUE.

	BEE standard	Uptime Institute / Green Grid standard
Category	Telephone exchange as Office building	Data center / IT Industry can be applied to Telephone exchange
Energy Conservation Criteria	Savings in KWH as compared to previous year.	PUE =     Total facility Energy consumption / Exchange equipment Energy consumption
Measurement	Energy consumption comparison with reference to previous year.	Energy flow for the year.
Effect of Addition / deletion of equipment	Not considered.	Considered.
Level of efficiency	No such criteria	Depending upon Climate zone “Level of Efficiency” may be proposed
Evaluation	Can not be done.	Excellent for understanding how effectively telephone exchange infrastructure is delivering energy to its exchange ( IT )equipment.

        References:

1.                DOT website.

2.                IREDA website

3.                White paper on Guidance for calculation of Efficiency (PUE) in Data Centers by APC.

4.                White paper on Usage and public reporting Guidelines for the GREEN GRID’S Infrastructure Metrics (PUE/DCIE) by The Green Grid.  http://www.thegreengrid.org/Global/Content/white-papers/The-Green-Grid-Data-Center-Power-Efficiency-Metrics-PUE-and-DCiE

Case study Telephone Exchange Alkapuri Vadodara, Gujarat.

Power Plant /  UPS load details- TE Alkapuri
SMPS RECTIFIER				62.1	KW		FOR  OCB , BB , OFC,TRANSMISSION, BTS equipment.
Year	Month			P/P 1	P/P2		Total		Year		Month		P/P 1		P/P2		Total
				E10B	OCB		amp						E10B		OCB		amp
2012	April			515	651		1166		2013		April		524		674		1198
	May			513	645		1158				May		538		664		1202
	June			505	663		1168				June		525		605		1130
	July			496	631		1127				July		515		607		1122
	Augest			511	630		1141				Augest		500		640		1140
	Sept			516	653		1169				Sept		498		632		1130
	Oct			505	633		1138				Oct		520		677		1197
	Nov			511	624		1135				Nov		535		685		1220
	Dec			511	630		1141				Dec
	Jan			513	645		1158				Jan
	Feb			511	612		1123				Feb
	March			501	650		1151				March
							1149										1157
					Say		1150								Say		1150
UPS	8.1 KW			For DOT SOFT SERVER
Year 2012-13
Month/ Year		Actual Max. Demand (KVA)	Bill Amount			TOTAL  GEB KWH		PF Rebate		Exchange load ( UPS + SMPS )		Exchange Energy consumption		PUE
Apr-12		297	1197697			169116		20611		77		57362		2.95
May-12		305	1111428			180756		22030		77		55512		3.26
Jun-12		322	1305045			186630		23329		77		57362		3.25
Jul-12		299	1104402			158352		19398		77		55512		2.85
Aug-12		274	1014346			153012		19126		77		57362		2.67
Sep-12		269	1098744			161988		20248		77		57362		2.82
Oct-12		289	994543			145758		18221		77		55512		2.63
Nov-12		247	897327			134808		16514		77		57362		2.35
Dec-12		232	955490			142056		17401		77		55512		2.56
Jan-13		221	779548			114942		13793		77		57362		2.00
Feb-13		230	866671			128376		16063		77		57362		2.24
Mar-13		251	799971			118146		14473		77		53662		2.20
			12125212			1793940		221207						2.65
Average						147711
MAX		322				186630
MIN		221				114942

Following Energy Conservation Measures Implemented.

1. Air Flow Management for OCB local, OCB Tax, BB & Transmission room. AC plant temperature less than switch room indicates short cycling of supply air, provided additional supply air duct for Targeted supply.

             Improved airflow management will increase both the efficiency and capacity of cooling equipment.

2. Increase in return air area , rearrangement of return air grills for targeted return.

3. Reduction of heat gain through glass windows.

4. Avoiding use of diffuser for supply air openings, which reduces short cycling of supply air.

After implementing Energy Conservation measures, there is improved utilization of electrical energy.

PUE improved to 2.30, Building now can termed as energy efficient from average, which can be further improved by reducing area to air conditioned and providing localized cooling equipments.

Year 2013-14
Month/ Year	Actual Max. Demand (KVA)	Bill Amount	TOTAL  GEB KWH	PF Rebate	Savings in KWH as compared to 12-13	Exchange load ( UPS + SMPS )	Exchange Energy consumption	PUE
Apr-13	263	1023666	152160	18639	-16956	77	57362	2.65
May-13	290	98800	159894	16648	-20862	77	55512	2.88
Jun-13	247	1069902	155172	15497	-31458	77	57362	2.71
Jul-13	292	879377	125754	16033	-32598	77	55512	2.27
Aug-13	238	912610	133722	17404	-19290	77	57362	2.33
Sep-13	252	997896	145824	18979	-16164	77	57362	2.54
Oct-13	240	871362	126588	16475	-19170	77	55512	2.28
Nov-13	229	951934	136284	18100	1476	77	57362	2.38
Dec-13	200	723256	102088	13286	-39968	77	55512	1.84
Jan-14	209	753908	106724	14174	-8218	77	57362	1.86
Feb-14	170	829504	115376	15016	-13000	77	57362	2.01
Mar-14	189	736240	101796	13519	-16350	77	53662	1.90
		9848454	1561382	193770	-232558			2.30
Average			130115
MAX	292		159894
MIN	170		101796
Savings wrt 12-13		2276758	232558	for Year
			17596	per month