Greenhouse | Electrical Systems | Climate Control | Australia

Monitor Your Greenhouse Electrical Systems with Smart Control

Most greenhouse growers throughout Australia have Motor Control Boxes to monitor their electrical systems. They are controlled by the climate control computer and monitor the greenhouse’s limit switches in the motor as it switches power to the motor, opening vents or screens. Many growers have experienced problems, however, which include:

The motor over-running limit switches, causing overload to trip. If this happens on a hot, cold, rainy or windy day, the results can be catastrophic. This is a very common problem, especially with vents.
Contactor fusing, forcing the motor to run past its limit switches. While this will normally trip out the overload, once it is reset, it will continue in the wrong direction.
Domestic electricians often have trouble installing them, resulting in either problems or high installation charges.

Smart Drive Circuitry Diagram

Over the past 15 years, Powerplants have experienced these problems and many more and used this experience to develop the Smart Motor Control Box (MCB). There are many benefits that the Powerplants Smart MCB can offer:

It’s easier to install - if the motor is wired so that it runs the wrong way at the time of installation - just flick a switch and the MCB will correct the wiring internally, saving installation costs.
The installer does not have to worry about co-coordinating the limit switches with the motor direction - the Smart MCB will automatically make the correct association during the set up procedure.
The input signals from a controller can be configured to be 24VAC or voltage free contacts.
If a motor over-runs the working limit switch and hits the safety limit switch the MCB will not trip the overload. Better than that, it will reverse the motor off the safety switch and not allow the motor to run towards it again until it has moved further away from the limit switches.
If a single phase motor gets a signal to go in the opposite direction before it has come to a stop, it can continue to run the same way instead of reversing. The smart MCB prevents this from happening. It allows the motor about 1.5 seconds to come to a stop before it passes on a signal to go in the reverse direction. This works equally well for both automatic and manual operation.
The smart MCB is tamper proof. It constantly monitors the state of all the limit switches and the contactors.
If any condition that could be harmful is detected the smart MCB will trip the power and set an alarm. Even if someone removes the lid and directly operates the contactors the MCB will monitor that and if necessary it will trip the power and set an alarm.
Coded alarms for ease of use:
- The smart MCB has an alarm LED (light) and a buzzer. When an alarm condition is detected the LED will flash and the buzzer will beep. If the alarm condition could result in damage to the motor (or the equipment it drives) the power to the motor will be cut.
- The alarm is coded so that the operator can tell what caused it. All the operator has to do is count the number of flashes or beeps. By referring to a simple table the cause of the alarm is identified.

Smart Drive Control Panel

If your greenhouse electrical system goes down, how will you monitor and control the climate?

Here are two examples of how the Smart MCB can detect a fault that other MCBs would not detect.

A contactor fuses shut. The next time the contactor is supposed to open, but doesn’t, the Smart MCB will cut the power to the motor and set an alarm
A safety limit switch has been tripped and then someone manually operates the contactor to try and back it off. Unfortunately they choose the wrong contactor (yes - it does happen) and damage could result if the motor is allowed to go. The Smart MCB will immediately cut the power and set an alarm.

The Smart MCB either fixes the problem itself or sets off an alarm for all but the most critical problems, which could save your entire crop.

Powerplants Smart Motor Controllers were introduced last Spring, and since then have had numerous instrallations. Here is what David Pearson from Lonsdale Hydroponics had to say about the replacement of his old MCB’s with the new Smart MCB’s:

“We are very happy with the new Smart MCB’s. Before installing them we were getting over runs regularly. We haven’t had one since they were installed. The over run problem has been fixed, its fantastic - very happy.”