Remote Station Engineering - Power Systems

This page is maintained with specifications for power components which represent the current best-practices employed by UNAVCO in Polar Permanent GPS Station designs. Specifications are subject to change as the design evolves, however the most current design will reside here.

Technical Notes

Complete lists of permanent station components and tools, and a weight calculator, are maintained on the Documentation page.
Test Series: SLA battery cold performance Gel vs. AGM
Test Series: Effect of long term cold storage on SLA batteries
Power Analysis: Solar panels and SLA batteries required for year-round operation at high latitude

Electronics and Power Regulation

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
Power System Schematic			PPS-DC-002 revC	Power distribution to electronics from solar, wind, and batteries.
Electronics Assembly	Note: above photo shows "basic" board (also configured with NetRS, Xeos XI-100, and weather station cabling). Note: above photo shows "full" board (also configured with NetRS and two 9522B modems).	UNAVCO	"Basic" board, wired for 2 solar panels, 1 main battery bank PPS-DC-008 revA: sheet1 sheet2 sheet3 "Full" board, wired for 4 solar panels, 2 wind turbines, 1 main + 3 aux battery banks PPS-DC-007 revG: sheet1 sheet2 sheet3	System electronics are mounted to 23" x 16" x 1/2" LDPE board. All components are immediately accessible when enclosure lid is opened. Cables are routed cleanly.	13	1 (26"x16"x4")	DC breakers, DIN rail, solar and wind regulators. Spring-loaded terminal blocks and integral regulator leads to avoid screw loosening. Diodes inline with solar and wind turbine inputs to prevent system failure due to external cable damage and eliminate reverse current backflow through solar panels when dark.
Solar Regulator		Flexcharge	NC30L12-M-UNVTC	Solar charge regulator with outstanding cold performance and LVD circuit (OFF at 11.0V ON at 12.9V) Uses UNAVCO custom temperature compensation for Deka gel cell batteries. Regulator power draw is < 0.1 Watt.	Incl. in electronics assembly	Incl. in electronics assembly	Proven reliability worldwide, including polar stations. Available with integral leads, eliminating screw terminals which can loosen over time. Temperature compensation curve optimizes charge level without overcharging across -40C to +40C.
Wind Regulator		Flexcharge	NC25A-12-M-UNVTC	Wind charge regulator with outstanding cold performance. Functions seamlessly in parallel with solar regulator when charging the same battery bank. Uses UNAVCO custom temperature compensation for Deka gel cell batteries. Regulator power draw is < 0.1 Watt.	Incl. in electronics assembly	Incl. in electronics assembly	Handles wind turbine power independently of solar power. Diverts excess power to a dump load when batteries fully charged. Available with integral leads, eliminating screw terminals which can loosen over time. Temperature compensation curve optimizes charge level without overcharging across -40C to +40C.
Electronics Foam Housing		R&B Sales	PPS-EN-006 revD	Foam housing insulates critical electronics: GPS receiver, solar and wind regulators, timer switch, and modem.	1	1 (16"x16"x5")	Effectively conserves heat around temperature-sensitive electronics.
Heating Pad		STEP Warmfloor	MEP-23-2-22W	Mylar encapsulated self-regulating heat pad. Available in range of sizes, shapes, and nominal resistance values. Primarily used as divert load for wind turbine. Can also be powered by solar panel to heat batteries for improved charging in early and late summer.	3	<0.5	Rugged vinyl-encapsulated design. Electro-plastic material increases resistance with increasing temperature. Large size results in low power dissipation per area without hot spots.
Electronics Assembly for Polar Plateau System		UNAVCO	PPS-DC-006 revTEMP sheet1 PPS-DC-006 revTEMP sheet2 PPS-DC-006 revTEMP sheet3 Note: these drawings are preliminary and intended as general specs only.	Instrument board resides inside vacuum-insulated chamber; components arranged so all LED's are easily visible. Breaker board is located on top of vacuum chamber to allow easier access to breakers and power/RF connectors at enclosure wall. Small notch in vacuum chamber allows cable pass-thru.	16	1 (16"x16"x4")	System electronics are mounted close together to conserve heat. Electronics are contained inside vacuum-insulated chamber with batteries to maximize battery temperature if heating from solar panel and/or wind turbine fails.

Solar Panels

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
80-Watt Solar Panel Assembly		Solar panel: Sharp Bracing: T & E Tech 3772 Puritan Way #9 Erie CO 80516 858-229-8478 Backing: B&B Machine and Grinding Gland fittings: Thomas and Betts	Solar panel: NE-80EJEA Bracing: PPS-SP-003 revF Backing: PPS-SP-004 revF Assembly: PPS-SP-007 revA sheet 1 sheet 2 Gland Fittings: 2921AL (straight) 141AL (locknut) 4961AL (90 deg)	12VDC, 80-Watt solar panel, strengthened to resist high winds. Aluminum angle braces are bolted to top and bottom sides of panel. Backing is 12 gage aluminum sheet, bolted to braces for wind hardening. Internal ribs are one wood 2x4 and two 2" wide strips of 1.5" thick blueboard foam. Ribs are glued to back side of solar panel with Loctite Power Grab adhesive. Panel attaches to frame with four saddle clamps (see Structural page).	Panel only: 21 Panel assembly: 42	Panel only: 1 (47.25"x21.1"x1.8") Panel assembly: 1.5 (47.25"x24.6"x1.9")	Robust structural frame and panel face. Sealed junction box, good screw terminals, and knockouts for 1/2" cable gland fittings. Angle braces increase rigidity and allow mounting to frame. Backing protects back side of panel from abrasion by wind-blown debris, and with internal ribs, creates a sandwich between backing plate and solar panel for added strength. Gland fittings provide excellent strain relief for cable.

Wind Turbines

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
High Speed Wind Turbine Assembly	Note: above photo does not show 3-phase rectifier box. Note: above photo shows weatherpack connector on 2-conductor cable, and shorting plug.	Wind turbine: Forgen Renewables Adapter plate: B&B Machine and Grinding Pipe coupling: Kee Klamp Pipe extension: T & E Tech (info above)	Wind turbine: Forgen 500-LT side-mount 3-phase Adapter plate: PPS-TF-010 revB Pipe coupling: 14-8 Pipe extension: PPS-TF-016 revA NOTE: Specify following options when ordering Forgen 500: - Low-temp bearings (C3 clearance, -60C lubricant) - Low-temp cable - High-gloss black polyester coating - Side-mount version with top bearing - 3-phase model, delta wiring - 8 inch length of 3-conductor cable between turbine stator and rectifier box - Rectifier box mounted to underside of bottom bracket arm - 16 foot length of 2-conductor cable exiting rectifier box	Robust, low-power turbine for high wind environments. Small and light enough to mount directly on structural frame. Attach two adapter plates to Forgen 500 side-mount bracket with 3/8-16 x 1-1/4" flathead bolts and permanent loctite. Turbine attaches to structural frame and pipe extension with two saddle clamps and one straight pipe coupling fitting. Pipe extension is 18" length of 1.5" sch40 aluminum pipe.	Including mount: 20	1.5 (20"x8"x8")	Lightweight and simple to install, used by UNAVCO and others at dozens of polar locations. Overall reliability has improved substantially from earlier generation models, with side-mount design and strengthened blade attachments. Output power has also increased with 3-phase design.
Low Speed Wind Turbine Assembly		Wind turbine distributor: Xylem / Cleghorn-Waring / LVMshop Bearings: Bearing Service Mount adatper: T&E Tech (info above)	Wind turbine: Aero4gen LVM412-1.5 non-furling Bearings: NSK-6302VVC3/LG68 NSK-6001ZZC3/LG68 NSK-6003VVC3/LG68 Mount adapter: PPS-TF-005 revA (use with Thomas and Betts 2921AL cable gland fitting)	Powerful, lightweight turbine suitable for mild to moderate polar wind regimes. Deployed with outstanding success at three locations, two on Polar Plateau and one at UNAVCO alpine test station. Manufactured with custom blade and yaw bearings for operation in extreme cold, using class C3 internal clearance, cleaned and re-packed with LG68 (Royco 27) low-temp lubricant. Remove yaw bearing water seal to further reduce low-temp friction, then use silicone to seal wire exit point.	Including mount and cable: 28	Assembled: 23 (48"x34"x24") Disassembled: 4 (48"x12"x12")	Lightweight, powerful wind turbine with low startup speed and good survivability. Aerogen model outperformed two other micro wind turbines in laboratory and cold chamber testing. With these bearings, turbine maintains low turning torque for blades and yaw bearing to -70C. Can be regulated with Flexcharge NC25A charge regulator and a network of heat pads.

Batteries

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
Sealed Lead-Acid (SLA) Battery		East Penn Deka Identical battery also supplied by MK Battery	8G31ST Deka Solar Battery Brochure[pdf] Deka SLA Battery Technical Manual [pdf] Deka VRLA Battery MSDS [pdf]	12V, 98 amp-hour, deep cycle, sealed lead acid gel cell for solar applications. ST model with two threaded stud terminals.	70	1 (13"x9.5"x7")	Gel-cell technology used by UNAVCO and others at multi-year polar installations with good success. Very little difference observed in performance between AGM and Gel batteries for remote polar instrument stations.
SLA Battery Wiring Harness		Optimum Systems	PPS-DC-005 revB How to connect batteries in a ring circuit, in large or small enclosures: PPS-DC-004 revD sheet 1 sheet 2	2-way Weatherpack connectors with 13" red/black leads and 3/8" heavy-duty crimp ring terminals. Connect batteries in a ring circuit so that any one broken connection will not cause loss of power.	Incl. in battery	Incl. in battery	Robust connectors. Reduces field wiring time and accidental mis-wiring. Batteries are pre-wired with male/female harness elements prior to deployment.
SLA Battery Transport Case		Battery Mart	BOX-27	Inexpensive transport case for batteries. Fits one 8G31 battery.	4	1 (16.5"x10.5"x8.75")	For air transport within the USAP as well as most Arctic areas, batteries must be enclosed in separate carrying cases.
Lithium-ion Battery		Tadiran Distributed by EVS Supply	TLP93101/E/L TL-4930 spec sheet [pdf] HLC-1550A spec sheet [pdf] TL-4930 MSDS [pdf]	18V, 190 amp-hour, non-rechargeable, lithium thionyl chloride battery pack provide backup power for GPS receiver. Each pack consists of 50 TL-4930 and 5 HLC-1550A in series-parallel arrangement. Batteries are hazardous materials but can be air-shipped when in manufacturer's original packaging. UN number 3090.	Each pack: 12	Each pack: 1 (13"x6"x3")	Expensive and non-rechargeable, but very high power density and power delivery in extreme cold (55% capacity at -50C). Pack is engineered to deliver specific steady-state and transient currents. Can be used to provide winter backup power to GPS receiver and/or lighten overall system weight.
Lithium Battery Wiring Harness		EVS Supply		2-way Weatherpack connectors to connect 10 lithium battery packs in parallel	Incl. in battery	Incl. in battery	Robust connector, reduces field wiring time and accidental mis-wiring. Order batteries pre-wired with mating connectors.

Power Cables and Connectors

Power connections use commercial versions of MIL-DTL-5015 bayonet circular connectors. Connectors are a well-proven design and are environmentally sealed. Large form factor and 1/4 turn bayonet engagement allow easy connection with gloved hands. Unique pin arrangements for solar (2-pin), battery (4-pin with two blanks), wind (4-pin with two blanks, rotated 120 degrees), and met (5-pin) prevent mis-engagement. Connectors use large-size crimp contacts.

All power cable assemblies made with Polar Wire cable, suitable for all polar locations. Connectors on external cables are potted and overmolded for sealing, strain relief, and ease of handling. Connectors on internal cables are potted and finished with adhesive lined heat shrink for sealing and strain relief, with ends stripped and tinned for insertion into terminal blocks.

Use bulkhead connectors to avoid hard-mounting cables to enclosure wall. Bulkhead connectors use O-ring seal.

See Structural page for drawing of connector layouts on enclosures.

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
Power Cable		Polar Wire Products	AUF-TC142	14 gauge, 2 conductor power cable (red and black). Connectors and cable assemblies can also accept 12 gauge, 2 conductor cable (P/N AUF-TC122).			Extremely rugged cable, tested flexible to -50C. Suitable for use at all polar locations.
Cable Assembly: Internal Solar		PEI Genesis Contact for all UNAVCO parts: PEI Genesis Arizona Office	Ask	Connects Power Board wind terminals to solar pass-thru connector on enclosure wall.
Cable Assembly: Internal Battery		PEI Genesis	Ask	Connects Power Board battery terminals to battery pass-thru connector on primary enclosure wall. Also connects auxilliary battery bank to auxilliary enclosure wall if more than one battery enclosure used.
Cable Assembly: Internal Wind		PEI Genesis	Ask	Connects Power Board wind terminals to wind pass-thru connector on enclosure wall.
Cable Assembly: Internal Met		PEI Genesis	Ask	Connects Power Board load terminals and GPS DB9 serial port to met pass-thru connector on enclosure wall.
Cable Assembly: External Solar		PEI Genesis	Ask	Connects solar pass-thru connector on enclosure wall to solar panel.
Cable Assembly: External Battery		PEI Genesis	Ask	Connects battery pass-thru connector on primary enclosure wall to pass-thru connector on auxilliary battery enclosure wall if used.
Cable Assembly: External Met		PEI Genesis	Ask	Connects met pass-thru connector on enclosure wall to Vaisala weather station.
Connector: Wind Turbine Cable		PEI Genesis	ITT Cannon CB6U18-10SX0	Straight cable plug to connectorize wind generator cable. Assemble with following hardware: CB12-12S size 12 crimp contact, 12 AWG 192990-2050 Daniels AF8 manual crimp tool 995-0002-052 Daniels TH452 crimp tool turret head 225-0018-000 wire hole fillers DP125 3M Scotch Weld 125 epoxy EPX-APPLICATOR epoxy applicator tool EPX-NOZZLE epoxy applicator mixing tip CPA-100-1000-BLK adhesive lined heat shrink
Cable Assembly: External Wind		PEI Genesis	Ask	Pre-terminated cable assembly for wind turbine. Can splice to existing wind turbine cable instead of terminating cable as above.
Heat Shrink Tubing		PEI Genesis	CPA-100-XXXX-BLK (XXXX = un-shrunk diameter in inches x 1000)	Adhesive-lined heat shrink tubing for sealing and strain relief of power and RF cables.
Connector: Solar Bulkhead Pass-thru		PEI Genesis	ITT Cannon TBF18-3PSB	Bulkhead pass-thru connector mounted to wall of primary enclosure.			See Structural page for drawing of connector layouts on enclosures.
Connector: Battery Bulkhead Pass-thru		PEI Genesis	ITT Cannon TBF18-10PSB	Bulkhead pass-thru connector mounted to wall of primary enclosure.			See Structural page for drawing of connector layouts on enclosures.
Connector: Wind Bulkhead Pass-thru		PEI Genesis	ITT Cannon TBF18-10PSXB	Bulkhead pass-thru connector mounted to wall of primary enclosure.			See Structural page for drawing of connector layouts on enclosures.
Connector: Met Bulkhead Pass-thru		PEI Genesis	ITT Cannon TBF18-11PSB	Bulkhead pass-thru connector mounted to wall of primary enclosure.			See Structural page for drawing of connector layouts on enclosures.
Nut Plate		PEI Genesis	M85528/2-18A	For mounting bulkhead pass-thru connectors with 4-40 x 1/2" socket head cap screws.			Makes life much easier when assembling. See Structural page for drawing of connector layouts on enclosures.
Seal Ring		PEI Genesis	980-8554-000	Internal seal ring for all power connector plugs above.			Spare seal rings. These rings inside connectors can occasionally fall out and connector will not engage properly.
Cable Assembly: Panel Mount Solar		PEI Genesis	Ask	Panel-mount version of above "internal solar cable". Finds occasional use in permanent stations.
Cable Assembly: Panel Mount Battery		PEI Genesis	Ask	Panel-mount version of above "internal battery cable". Finds occasional use in permanent stations.
Cable Assembly: Panel Mount Wind		PEI Genesis	Ask	Panel-mount version of above "internal wind cable". Finds occasional use in permanent stations.