PICTURES: ST2-5A BOARD BASIC CONNECTION SCHEMATIC DIAGRAM

The ST2-5A, 10A and 20A are light seeking tracker controls designed for DC motor systems (typically linear actuators) with up to 48VDC

maximum operating voltage (minimum operating voltage=10VDC). In unobstructed sunlight it typically tracks within 0.25 degree of actual

sun position.

The following “normal” operating modes apply:

1) Useable sun—the unit points toward highest illumination, which is usually the sun’s disk but may be “the brightest part of the sky”

during variable cloud conditions.

2) Mostly obscured sun (e.g. cumulous clouds with breaks)—unit pauses at last “valid” control point to wait for conditions to change.

3) Heavy overcast or night—unit moves to “park” position to await light level recovery.

The PARK position is determined by S1-2 (East or West) and S1-3 (V=array vertical, HORIZ=array horizontal).

Abnormal conditions—typically, motor failure or mechanical system jam:

Tracker will attempt to move the array. If motor overcurrent condition is sensed, tracker will terminate drive and flash the PAUSE LED.

Indicators on the control PCB: PWR, PRK, PAUSE, E/W DRIVE, UP/DN DRIVE.

Notes on initial installation, power up and adjustments.

The remote sensor needs to be attached to the array frame such that the mounting surface of the sensor is parallel with the plane of the array—where on the array is not critical as long as the sensor receives unobstructed sun during the hours when the array is expected to track.

One second after power is applied, the tracker is active. If the ambient light level is above the track threshold, it will then commence tracking.

There are three trimpot adjustments, two are for tracking accuracy and are used to compensate for component variations and slight misalignments of the remote sensor. The third is to adjust the light level at which the tracker control changes from track to pause and pause to park—this single adjustment is for both the pause and park threshold—they’re approximately proportional.

Trimpot sensibilities:

Light Level—Clockwise for lighter Pause/Park threshold.

Position trim E/W—Clockwise for West.

Position trim UP/DN—Clockwise for Down (toward horizon).

S1-1 (DLY) on the PCB controls the delay function. The idea here is that, during the initial installation, this is in the OFF position. In this state, everything happens “instantaneously”—a useful condition when tweaking the track trimpots and setting the PAUSE/PARK threshold. When the DLY switch is in the ON position (for normal, unattended operation), the following delays are added to the system operation:

A ten second delay is added to tracking corrections so that a requirement for a position change must remain constant for 10 seconds to be considered valid. This is to reject transient events such as something flying over the sensor and, in cases where the sensor is shaded by moving vegetation during part of the tracking day, to hold off and/or reduce movement during back and forth shading events which aren’t representative of true sun position and are not dark enough to invoke the PAUSE function.

A ten minute delay is added to the change from PAUSE to PARK. This is for conditions of changing cloud cover (where the sun occasionally pokes through) to keep the tracker from sending the array back and forth between PARK and TRACK positions. Light conditions must remain below PARK threshold for 10 minutes or more before the controller will allow movement. (There is only a 10 second delay when changing from PARK to TRACK.)

The tracker control PCB needs to be housed indoors or in a weatherproof enclosure.

The following flavors of product are available (choose appropriate shipping option below):

ST2-5A-2-RS2 Dual axis light seeking tracker control 5A per axis with remote light sensor and 10ft cable: $155

ST2-10A-2-RS2 Same as above except up to 10Amps maximum motor current per axis. $205

Single Axis Versions:

ST1-5A-2-RS1 Single axis light seeking tracker control 5A per axis with remote light sensor and 10ft cable: $140

ST1-10A-2-RS1 Same as above except up to 10Amps maximum motor current: $190

Accessories:

EC2 Extra remote sensor cable (4 conductor shielded) sold on a per foot basis. $0.50/ft.

UM2 Hard copy of user manual. If you have email, a FREE PDF version of the manual will be sent with shipping notice. If you

need printed copy, a small charge applies. $2 each.

Shipping:

USA GROUND $10

USA AIR $15

CANADA GROUND $15

CANADA XPRESS POST $20

REST OF THE WORLD SURFACE $30

REST OF THE WORLD AIR $60