Contents

Description
Specifications
Operation
Installation
Basic Field Service
Block Diagram
Connection Diagram
Alarm & Serial Port Connection

Description

The charge regulation and load control voltages are fully adjustable. The display is used to show battery voltage, load voltage, solar array voltage, charge current and load current.

On the charge side, two stage boost/float regulation is used. The regulation voltages are adjustable via the keypad and display. Up to four stage bank switching can be used which allows taper charging in the boost mode and low speed switching regulation in the float mode. Coupled with controlled rise and fall time switching, this allows the regulator to achieve very low levels of audio and radio frequency emissions. These low levels of interference make the unit particularly well suited to operation of telecommunication equipment in weak signal areas.

A Temperature sensor may be added to compensate for changes in battery temperature.

The load disconnect feature forces load disconection when the battery voltage is too low or too high. The low and high disconnect voltages are adjustable. A load current up 50 amp can be drawn.

The control board uses a microcontroller integrated circuit coupled with a 16 x 2 line liquid crystal alphanumeric display and a 12 key membrane switch keypad. The display and indicators will automatically turn off after 10 minutes if no key has been pressed. Set up data is stored in non-volatile EEPROM. To protect against program loops or errors, a hardware watchdog timer is used to automatically force a processor reset if an error should occur.

The use of a microcontroller allows the unit to collect statistics on the performance of the power supply system. It logs daily charge and discharge amp hours and battery maximum and minimum voltages for 32 days. This makes system performance assessment easier.

The use of a sealed membrane keypad rather than a set of switches and potentiometers eliminates the need for elaborate sealing against high humidity and the risks of settings drifting.

Alarms for Low battery voltage, High battery voltage and Load disconnected are available via a pair of voltage-free relay contacts.

For more accurate remote control and monitoring, a serial port is available which allows remote examination of the performance of the system and adjustment of the operating parameters if necessary. This feature can help to reduce the need for high cost field trips into areas where access is difficult. The serial port can be connected to a modem so that the unit may be dialed up over the switched telephone network.

Simple modular construction allows field repair to be done in a short period by changing over modules. Two special test modes can be enabled to help in rapid testing of the unit.

The unit is designed to be housed in a cabinet 300W x 400H x 210D mm which is sealed to IP66 standard. The circuit boards have a conformal silicone coating applied and the aluminium parts are either anodised or powder coated.

Circuit breakers are provided to protect the batteries against fault conditions.

This version of the regulator is positive ground. That is, it switchs on the negative side.

To guard against lightning, surge protection has been included on the array inputs and the control logic board. High power Transorb diodes are mounted across each bank switch, the load switch and the input to the logic board. All FET gates are protected with zener diodes from each gate to source. All sense inputs have additional series resistance to help protect them.

This operating manual contains a description of the operation of the control cabinet, a set of specifications, an installation guide and a guide to setting the voltage adjustments.

Operation

Charge regulator
Charge regulators are used to protect storage batteries from overcharging. This regulator uses a two state boost/float type control scheme.

The photovoltaic panels are grouped in banks. In the boost mode, all banks are connected so that maximum charge current flows into the battery until the battery voltage reaches the preset taper voltage (adjustable 26-34V). As the battery voltage continues to rise, banks are progressively disconnected (begining with bank D) until only one bank is charging. A time delay occurs between changes in bank connection. (Adjustable 0.1-6.0 minutes) This is necessary to allow the new conditions to stabilise and prevent oscillation.

Banks A and B can be paralleled and the unit used as a three bank regulator by selecting the 3 bank option in the control set menu. Similarily in 2 bank mode A,B & C are paralleled and in 1 bank mode all four are paralleled. This tapered charging results in less corrosion of the plates and allows better charging of batteries in poor condition. When the battery will sustainthe preset boost maximum voltage (adjustable 27-34V), the regulator will switch into the float mode.

In this mode, the charge current is reduced to that level which is necessary to keep the battery voltage within a preset float range (adjustable 24-30V). Floating the batteries in this voltage range helps to keep them fully charged and prolongs their life. To eliminate audio interferance, the bank switching in the float mode can be no faster than one change per second.

When the battery voltage remains below the boost cut in voltage (adjustable 24-27V) for ten minutes, the regulator will switch back into boost mode and will remain in boost mode until the voltage rises again to the boost minimum.

The charge curent switching is done with rugged power MOSFET devices. These devices result in a very low voltage drop across the bank switches when on and enable the unit to achieve very low operating power dissipation. They are also arranged so as to block reverse current flow due to panel wiring shorts and solar night loss currents. This design eliminates the need for reverse blocking diodes.

The optional temperature sensor is able to compensate for battery temperature variations over the range 0-60°C.

Control Panel
An 8051 series microcontroller is used to control the unit. Voltages are measured using a 10 bit A to D converter and the processor compares these readings against those settings stored in an EEPROM memory chip. (Because the EEPROM is non-volatile, the settings will not be lost if there is a break in power.)

The controller uses a 16 x 2 line liquid crystal display to show its information and a 12 key keypad to select which information is displayed, or to alter the settings. (The display is a special extended temperature range version.)

To reduce the effects of noise and transients (or spikes), the voltage and current measurements are processed through a digital smoothing filter with a time constant of 0.5 sec.

Display on/off
To prevent the display being accidentally left on, the display will turn off if no key has been pressed for more than 10 minutes. To reactivate the display, press any key.

Display Selection
The functions of the various keys are:

Voltage Display
To display the battery or load voltage, press the corresponding key.Because of the smoothing filter, the meters have a settling time of about 1 second. Voltage range 0-100V, resolution 0.1V.

Current Display
To display the charge or load current, press the corresponding key. The current is measured by using current shunts on the switch board. Display values are filtered as above. Range is 0-102A, resolution 0.1A.

Solar Display
The solar display first shows the current from each bank and `on' if that bank is connected. By pushing the INC button the display will now show the open circuit voltage of the bank. By using the INC and DEC buttons, the user can select which bank is displayed. This feature can be used to check the performance of each bank.

Remote Monitor
The remote monitor key allows the user to select the communication speed and site number for the serial remote monitor and control facility.

View Data
The view data key allows the user to read the performance data logged by the controller. Each day, the controller counts the total charge amp hours, the total discharge amp hours and records the minimum and maximum battery voltages. These readings are stored in the EEPROM and can be viewed using the VIEW DATA button or via the remote monitor link. 32 days data can be stored.

To view the data, press the VIEW DATA button. The first display that appears is the information for the current day in progress. It shows the data collected during that day from midnight on.

On the top line of the display, the first number is the number of the day for which the information is being displayed. (0 is the current day). The next number is the minimum battery voltage and then the maximum battery voltage. On the bottom line, the first number is the charge amp hours and the second the dischargeamp hours .

By pressing the INC button, the data from the previous day will be displayed (day 1). Pushing INC again will move to the day before (day 2).

Further pushes of INC will contine back until day 32 after which it will return to day 0. The DEC button will move the other way.

To leave the status display just press another function key.

Control Set
This key allows the regulation levels to be set.Each press of the key will access a different setting. Adjust each variable using the INC (increase) or DEC (decrease) keys. Holding down the INC or DEC key will provide the fastest rate of change.

1. Maximum boost voltage This is the maximum voltage that the regulator will allow the battery to charge to before it changes to the float mode.
2. Taper voltage setting. This is the maximum voltage that the regulator will allow the battery to charge to, before it begins to reduce the charging current. The taper voltage must be less than the boost maximum voltage.

3. Number of banks. Select 1 to 4 bank mode.

4. Float maximum voltage.

5. Float minimum voltage. The regulator will try to keep the battery voltage between these levels. The smaller the gap between the maximum and minimum, the faster the float bank switching will be. For minimum bank switching noise, a gap of 1.0 - 1.4 volts is suggested.

6. Return to boost setting. When the battery voltage drops below this level, the unit will switch from float back into the boost mode.

7. Temperature Compensation setting. If a temperature sensor is attached, the temperature compensation feature can be enabled.About -5mV/°C/cell is normal. If no temperature sensor is connected, the setting MUST be 0 otherwise the regulator will assume that the battery is at °C and correct accordingly.

8. State Change Delay setting. Set time between bank connectionchanges in boost mode. Adjustable 0.1-6.0 minutes.

9. LCD temperature setting. This is a device to aid in protecting the control unit against condensation due to rapid cooling after a hot day in humid conditions. By using the display backlighting control, it is possible, with the aid of insulation in the top half of the enclosure, to keep the display warm enough to remain above the dew point and so keep the display dry. By leaving the bottom section of the control board uninsulated, condensation will occur first in this area, and tend to dry the air inside the enclosure. The control board senses the temperature in the top section of the enclosure and tries to keep it at the set temperature. Because of the limited power available, this will not be possible under very cold conditions, and the facility should be disabled by setting the temperature to 0. This facility should be used ONLY in areas subject to extreme humidity, and only during the wet season. A setting of 35 should be adequate for most conditions.

10. Viewing contrast. Adjust for best display contrast. (varies with temperature).

11. Time (of day). Set present time of day. The daily data is saved at 0:0 hours each day.

Pushing the control set button again will cause the display toreturn to the start of the menu.

Note: the new values entered will not be stored until you exit from the control set mode. (This is done by pressing any other display select key).

Load Disconnect Set
This key allows the battery voltages at which the load is disconnected and reconnected to be set. As a guide, the low battery load disconnect voltage should be in the range 22.6-23.4 and the reconnect level 25-27. There is an adjustable time delay before disconnection to prevent false disconnects due to transient loads.

When the battery voltage drops below the disconnect setting, the time delay counter begins.

If the battery voltage stays low for the whole time delay, then the load is disconnected, the load disconnected relay contacts open and the `ld dis' indicator comes on. When the battery gets back above the reconnect voltage then, after the time delay, the load will be reconnected.

As a safety feature, if the load current exceeds the current limit, disconnection will occur after only about 0.3 seconds. The settings are:

Setting	Range
Low battery disconnect	21-24V
Low battery reconnect	21-30V
High battery disconnect	26-36V

The high battery reconnect voltage is set to be 2 volt below the high battery trip voltage. The last setting is for the disconnect and reconnect time delays. It can vary from 1 to 250 seconds.

Alarms
Two alarm outputs are provided. These are low battery voltage and high battery voltage. Each has a led to indicate when it is active. The relay outputs are normally closed and open when active. The low battery alarm activates when the battery voltage falls below the load disconnect voltage plus 0.4V. It will turn off again at load disconnect plus 0.4V. The high battery alarm activates at boost maximum + 0.8V and deactivates at boost maximum-0.2V.

Meter Adjust
This allows the various meter scale factors and offsets to be adjusted. The correction range is limited to +/- 12%. These are adjusted in the factory and should not be re-adjusted without proper measuring equipment. The INC and DEC keys are used to adjust the value. There are slope and offset adjustments. INC and DEC control the offset directly. To adjust the slope or gain, hold SOLAR button down while using INC and DEC.Pushing the METER ADJUST button moves through the list.

At the start of the list, it is possible to enter the two test modes. TEST MODE A can be selected by pressing the INC button and TEST MODE B by pushing the INC button twice. Pushing the METER ADJUST key then starts the test mode.

Test mode A is useful for testing correct operation of the control system. In this mode, the controller works normally, except that all time delays are reduced to 2 seconds so that changes in state can be observed without wasting large amounts of time.

Test mode B is used for testing the switching hardware. The controller does not operate normally, but cycles each bank on and off in sequence, then the load, performs a test write and read to the EEPROM , cycles regulator though each operating state, sends data to the serial output and then repeats this. Pressing the INC button will pause the cycle until the INC button is pressed again. Pressing the DEC button will terminate the test mode.

Lightning Protection
The lightning protection circuitry consists of 3kW of transient absorbtion diodes across the charge switch fets. Zener diodes are also installed from the gate to the source of each fet to protect the gate oxide. The logic board has a 1.5kW transorb on the input and series resistance on each of the sense leads to protect the A to D inputs.

Manual Reset
A manual reset of the controller can be performed from the keypad. Push the METER ADJUST key once. While holding down the SOLAR ARRAY key, press the CONTROL SET key. The controller will now reset.




Installation


This section provides some notes on installation.

Mounting
The cabinet is sealed to IP55 standard and so can be installed outside if necessary. However, it is best if it is under cover and out of direct sunlight.

This control unit is designed for a maximum temperature inside the cabinet of 70°C. Without the cabinet, the unit can be mounted on the wall via the four 10mm mounting holes.

Temperature Sensor
If temperature compensation is to be used, attach the temperature sensor as shown in the connection diagram on page 12. The sensor is polarised, so take care to connect the wire with the stripe on it to the T- input as shown. The sensor acts as a current source which is proportional to temperature. This means that the cabling to the sensor can be extended without having to worry about voltage drops along the wire. The temperature sensor should be installed in good thermal contact with one of the cells.

Note: It is very important to get the polarity of the battery connection correct! If in doubt, check before connection with a meter or use a current limiting resistor in series with the batery lead until the battery polarity has been shown to be correct.

Start Up
Install the regulator with all the circuit breaker switches and the logic board switch off.

Turn on the logic board switch first. The small yellow led should come on indicating logic power is good. The alphanumeric display should also light up and display an identifying logo, then the battery voltage. If this does not happen, then check the battery polarity or look for loose connections. Check the plug between the logic board and the control board.

When the logic control is ok, turn on the load circuit breaker, check that the load current and voltage are correct via the keypad.

Finally, turn on the charge circuit breakers. Check each bank in turn using the SOLAR button on the keypad.

Clearing the Data Memory
It is possible to clear the 32 day data memory from the keypad. While in the VIEW DATA mode, press the CONTROL SET button and hold down for 1 second. The display now asks if you want to clear the data memory. To clear press the INC button. To exit without clearing, press any other key.


Basic Field Service
The SPSD was designed for fast easy field servicing. It uses four standardised circuit boards, the switch blocks, interface and control boards. By keeping spares of these boards, repair can be done by replacing the faulty board with a spare and returning the faulty board for base or factory repair. This reduces the need for staff training. The basic field repair procedure is:

Step 1
Using the spare control board and keypad, unplug the existing control board ribbon cable and plug in the spare.

Step 2
Put the controller into test mode B and verify the operation of each bank on the switch block and the interface board.

Step 3
If switchs are ok, replace the control board. If not, then install spare interface board and retest. If the switching is now ok, the interface board was faulty.

Step 4
Send the faulty boards back for testing or repair.

Switch Board Test Procedure


1. Put controller into TEST MODE B by pressing the METER ADJUST button, pressing INC twice and then pressing METER ADJUST again.

Using the INC key, pause the test in Bank A. Check that all LEDs are off. Check that the displayed charge current is what should be expected from bank A under the light levels at the time.
Check that the bank voltage is about the same as the battery voltage.
Remove pause by pressing INC again, and wait until bank B is being tested. Pauseagain (by pressing INC) and repeat the current and voltage comparisons for bank B. Check that all leds are off.
Repeat for banks C and D.
Check that the load current shown is appropriate. Check that the load voltage is the same as the battery voltage.
Check the result of the EEPROM test.
Pause the test in state 0. All banks should have a charge current flowing. The total charge current should equal the sum of the individual bank charge currents.
Continue through to state 4. The banks should switch off starting with bank D until no banks are on (state 4). Current should decrease as each bank is switched off.
Connect SI to SO to test serial port.

To terminate the test mode press the DEC button.

Installing a Temperature Sensor
The temperature sensor TS1 is supplied in a sealed polypropylene moulding with a 3 metre cable.

The sensor is electrically a current source which is proportional to temperature. It is electrically polarised. Care should be taken to connect it in the correct polarity. The negative wire (the one with the stripe) of the sensor connects to T-. The cable may be extended if it is too short.

The sensor must be installed in good thermal contact with the battery case. Do not place the sensor near but out of contact with the batteries. This will give false correction because the air temperature will not be the same as the battery temperature. Good thermal contact can be achieved in a variety of ways. Here are some suggestions.

1. Glue the sensor to the battery case.
2. Wedge the sensor in the gap between two batteries in the bank with a piece of foam rubber. The foam rubber will hold it against the battery as well as sealing around it.
3. Place the sensor against the battery and cover it with a duct tape strip which goes all the way round the battery and wraps back on itself a couple of times. This will prevent it coming undone easily.
4. Sit one of the batteries on top of it. A space can be cut in the support shelf and a piece of foam rubber used to hold it against the battery.
5. Wedge between the battery and the wall using foam rubber to insulate it from the wall.

Block Diagram
Sorry, this diagram is not yet available.

Connection Diagram




Alarm & Serial Port Connection
Sorry, this diagram is not yet available.





Home

Regulators

Developments

Specifications

Downloads

Suppliers

Resources

No Frames