Chapter 11 - System Components

Power supply – A heavy duty linear 12 volt DC power supply provides regulated and protected power to the system’s micro-processor boards, called Data Gathering Panels (DGP). The power supply also provides fuse protection for this power supply, and the 24 volt AC power transformer which is used to operate the system’s Relay Control Units. The power supply includes an On/Off switch, indicator lights, and fuses for both voltages.

Control voltage transformer – The transformer provides 24 volt AC power relay to the Relay Control Units and other low voltage relays.

Communications spider hub – The spider hub is the central distribution point for RS422 communications throughout all aspects of the system. Each spider hub can communicate to 12 or more houses. Additional spider hubs are added for larger installations. There is a smaller version for 1-6 house installations. Every spider hub includes complete lightning protection.

Data gathering Panel – This enclosure contains the specific data gathering panels (DGPs) needed for the functions used in each house. The DGP boards collect the sensor information, communicate it to the central computer, relay the control commands to the various relay control units (RCUs), operate On/Off fans and variable speed fans, feeders, etc.

Relay Control Panel – This is an 18 channel interface between the equipment being controlled, the computer control signals, and manual backup signals from thermostats and time clocks for automatic back-up protection in the event any computer problem. Also included is the computer watchdog signal which provides automatic switching of the devices being controlled in the event of a malfunction or power failure. It also provides for isolation of different control voltages, and source voltages.

Backup Thermostats – These thermostats are wired into the Relay Control Unit and are used only if the computer integrity signal is lost, If this happens, all the watch dog signals go away, and the thermostat runs the ventilation directly. This is the first level of backup protection. If any communication problem exists in the system, an alarm is issued by the System Watch Dog Timer Unit, and sent directly to an outside alarm system (the second level backup protection).

Fail Safe Thermostat – This thermostat goes in the warmest part of the house, so that in the event the temperature gets warmer than is safe, it breaks the computer integrity signal, and forces the ventilation back to manual thermostats. If someone were to enter an incorrect temperature target into the system and ignore all the alarms and warnings, this thermostat would interrupt the computer signal and cause the fans to run based on the thermostat settings (Third level backup protection).

Feed Auger Relay Control Unit – The Feed Auger RCU provides the controls signals to the feeders, and coordinates the feed times, the activation of the feeders, the inside cross auger, a surge bin, and the outside bin augers.

Feed Auger Monitor – This device connects to and monitors a feed auger to insure the auger is stopping and starting within a specified time during a feeding. Normally, the fill auger will stop and start. If it runs continuously, the feed bin may be bridged, or out of feed, and the broilers would not get their complete feeding. If the proximity switch to control the feed auger malfunctions, the auger may never start, again causing the broilers to go without feed. This device will cause the computer to issue an alarm if one of these problems occurs.

Power Monitor Panel – This panel provides input signals to the control system for the following events:

• Control voltage failure. If the voltage that engages the fan contractors is shut off or overloads, fans will not run. It provides an immediate alarm for this condition. There should be more than one control voltage source for ventilation. All voltages are monitored.
• Three-phase power monitoring. It provides input signals to insure that 3-phase power is present with the proper voltage, and phase balance.
• 24 Volt AC Monitoring. It monitors its own voltage and alarms if our control voltage fails. If this occurs, building ventilation automatically goes back to normal control.
• Fail-safe thermostat. It monitors whether its Fail-safe thermostat has activated, and issues an alarm for this event.

System Watch Dog Timer Unit – This is an independent timer that is tied directly to an alarm system. It is powered by the 12 Volt DC power supply supplying power to the data gathering panels. It is reset, and kept activated by a 3-second relay signal from the output of a data gathering panel. In the vent the timer loses power, or is not reset with 3 minutes, its issues an alarm indicating a computer malfunction. If the control computer were shut off, for instance, the timer would no longer be reset, and would time out and send the alarm. If any data gathering panel in the system does not communicate properly with the control computer, the control computer does NOT send the signal to reset the system water dog timer, and an alarm is issued as soon as the timer times out.

Variable Speed Motor Controller Device – This is a frequency drive that controls the variable speed of a 3-phase motor. It is used on fans that are controlled by variable speed.