Overview

The design of EKO Sun-Tracker, STR-21 and STR-22, are based largely on our considerable experience in the development of both hardware and software for sun-tracking systems. EKO sun-trackers are the instruments with easy setup and highly accurate sun-tracking. STR-21/22 have achieved worldwide recognition of its durability, accurate poiting and cost-effectiveness. Two models, STR-21 (single arm) and STR-22 (double arm), are available to suit your application.

Features

High accuracy

In the Sun-sensor Mode, a four-sensor Si-photodiode detection system, which is with the sensors mounted orthogonally each other, moves the tracker to point the sun. When the sun is obscured by clouds, STR-21/22 track the sun position by calculations, which is performed by an internal CPU. This mode is called Calculation Mode. Either of Sun-sensor Mode or Calculation Mode is automatically selected depending on the solar irradiance intensity. The factory-set threshold of solar irradiance is applied to select the mode. Clouds will not affect tracking accuracy because the threshold value is determined according to the solar irradiance at a corresponding air mass.

Durability

STR-21/22 have adopted a specially designed and trouble-free gear assembly called Harmonic Drive. The motion of the stepping motor is transferred to the gear to drive the shaft. This construction has accomplished long-term durability for extended outdoor use.

Easy installation

The aperture angle of the sun sensor is �}15°(30°full angle), and STR-21/22 precisely point the sun when the sun is located within the solid angle of the aperture. Therefore, precise adjustment of the pointing mechanism is not necessary for installation. Setting the tracker to the sun position in the range of the aperture angle is the only non-dispensable operation. Attached spirit level makes the leveling easy and precisely.

Worldwide use

STR-21/22 use an AC100-240V, 50/60Hz power supply. Sun tracking calculations are designed to set the latitude, longitude and time at any site worldwide.

Outline drawing (STR-22)

Shading ball assembly

Attachments

Specifications

Model	STR-21 Single arm	STR-22 Double arm
Driving method	Harmonic DriveGearing
Motor	Stepping motor
Motor operation	Half step
Gear assembly	Harmonic drive
Tracking mode	Sun-sensor mode and Calculation mode are automatically switched.
Accuracy	< 0.01 degrees
Resolution	0.009 degrees
Torque	12 Nm	24 (12+12) Nm
Payload	7kg balanced	15kg balanced
Temperature range	From -40 to +50°C
Altitude	All altitudes
Real time clock accuracy	�}2 ppm, Power-on at 25°C
Back-up battery life	3,650 days (power-on), 1,000 days (power-off)
Communication	RS-232C, 9600bps, 8N1
Control software	Microsoft Windows based software
Power consumption	AC100 to 240V, 50/60Hz, 50VA
Dimension	430(W) �~ 380(D) �~ 440(H) mm
Weight	11.5 kg	13.5 kg
Registered Trademark by Harmonic Drive Systems,Inc. in Japan, China, Korea, Taiwan

brochure