Regardless of which discharge mode settings page is displayed, the operator can change the discharge mode from any one of them. However, it is important to understand that in order to change discharge modes, the operator must be in Manual mode first before changing to any of the other available modes. For instance, if the dryer is currently discharging in AccuDry mode and the operator wants to change to TruDry mode, the operator must first select Manual mode, and then select TruDry mode.

In addition to being able to select the mode of discharge from any of these pages, the Manual, TruDry and AccuDry Settings pages also all contain the same information for the following tiles: Disch Speed, Disch Speed Alarms, and Mid-Grain Temperature Alarms.

Manual Settings

When discharging in Manual mode, the operator controls the speed at which the grain discharges at. This adjustable value is under the Manual Settings tile, next to the Set Discharge Speed, input box.

Each dryer model has a discharge capacity for every revolution of the metering rolls for profile dryers and sweep for tower dryers. These discharge capacities are used to calculate how much grain is being discharged from the dryer given a specific discharge speed. The chart below shows what these discharge capacities are in bushels per revolution and cubic meters per revolution.

The AccuDry Settings page is very similar to the Manual Settings page as well. The only difference, other than the component quick launches, is the "Set Discharge Speed" box displayed on the Manual Settings page has been replaced by values and information pertaining to AccuDry.

To understand the settings on the AccuDry Settings page, it is best to first have a good understanding of the AccuDry Technology and how AccuDry works.

Since the speed of the discharge impacts the mid-grain temperature, it is on any of these discharge settings pages where the operator can set the mid-grain temperature alarm limits. If the dryer is discharging and the mid-grain temperature exceeds the mid-grain temperature alarm band for a set period of time, the dryer will enter a Cool Down mode. The two alarm limits that can be entered that pertain to the mid-grain temperature are the Alarm Band and Alarm Band Delay.

Alarm Band

The Mid-Grain Temperature Alarm Band is the allowed deviation from the mid-grain temperature set point while the discharge system is running.

Alarm Band Delay

The Mid-Grain Alarm Band Delay is a user-defined time duration in minutes that will delay the Cool Down of the dryer after the Mid-Grain Band warning alarm has occurred. If the Mid-Grain temperature returns to the acceptable range within this time period, no shut down will occur.

AccuDry technology utilizes the Dryer Moisture Systems Dryer Master DM510 system. The DM510 system uses specially designed in-line moisture and temperature sensors located at both the infeed and discharge of the dryer. These sensors provide continuous moisture and temperature readings to the PLC, which is shared with the DM510 logic board.

The DM510 board uses this information to build an operating model of your dryer. As infeed moistures and drying conditions change throughout the day; AccuDry continuously calculates and automatically adjusts to the optimum discharge rate for current conditions.

AccuDry has two important advantages. First, in automatic mode, it can continually watch the dryer. It does not have to help unload trucks, load trains, or do any other jobs around the elevator that a normal dryer operator does throughout the day. The dryer receives the user's full attention.

Second, it has the benefit of continuous moisture information from both the infeed and discharge of the dryer, giving it a complete picture of all the grain in the dryer, and the grain exiting the dryer.

With this information, AccuDry does not have to wait to react to changes in the outlet moisture. It is able to adjust the discharge rate as the incoming moisture changes. For example, as wetter grain comes into the dryer, AccuDry begins to slow down the discharge rate just as the wetter grain reaches the hot zone.

VFD Frequency = 30 Hz

VFD Frequency = 36 Hz

The AccuDry mode of operation utilizes input signals from both the discharge moisture sensor and the infeed moisture sensor to control the dryer's discharge rate. When the AccuDry mode of operation is available, it will display it's corresponding toggle button under the TruDry button. Also, when on the AccuDry Settings page, an input will be made available which allows the operator to enter the target discharge moisture setpoint.

When running in AccuDry, similar to the guidelines that were provided for TruDry, the minimum and maximum discharge speed Operational Limits are important to the controller's operation. The AccuDry control algorithm will attempt to speed up and slow down the discharge to maintain the discharge moisture setpoint, and the amount of room that the controller has to work with is determined by the minimum and maximum speed setpoints. For example if the min/max speed setpoints are 10% - 100%, the range of speed output from the controller will be higher, which means the rate at which the speed changes will be higher. On the other hand, if the min/max setpoints are 30% - 75%, the controller can only operate within that band and only has a range of 45% to work with.

Similar to how the mid-grain temperature setpoint (used in TruDry) can be changed while in manual mode, so too can the discharge moisture setpoint (used in AccuDry) be changed while in manual mode. The only limitation is that the operator cannot change the discharge speed setpoint when running in TruDry or AccuDry.

In order to effectively use the AccuDry mode of operation, it is important to allow the dryer to get to a steady state operating condition for 2-3 hours upon initial installation (depending on the size of the machine and the incoming grain moisture) with a desirable and consistent discharge moisture output. Once this steady state condition has been met, the operator will confirm the discharge moisture setpoint that is desired and make any required changes. Also, be sure the minimum and maximum discharge speed Operational Limits are set to an accurate band.

From any of these discharge settings pages (Manual, TruDry, or AccuDry Settings pages), in the Disch Speed tile, the operator can set operational limits that pertain to the discharge speed. The two operational limits the operator can set are the max and min speeds the discharge can run at. With the operational limits in place, the user will not be able to enter a speed in the Set Discharge Speed box of the Manual Settings page that exceeds these limits.

Setting Discharge Speed Alarm Limits

Again, from any of these discharge settings pages, under Disch Speed Alarms, the operator can set alarm limits that pertain to the discharge speed. There are two types limits: high limits and low limits. There also two types of alarms: warning alarms and critical alarms. If a warning alarm limit is exceeded, the control will trigger a warning message to be displayed on the HMI screens. If that particular reading continues further off course and exceeds the critical alarm limit, the dryer will shutdown and a critical alarm message will appear on the HMI screens.

High Speed Critical

If the Current Speed exceeds the value entered for the High Speed Critical value, the dryer will shut down. The input value for this High Speed Critical alarm must be equal to or greater than the value entered for the High Speed Warning value. To expand the allowable input range for the High Speed Critical value, the High Speed Warning value may first need to be adjusted.

High Speed Warning

If the Current Speed exceeds the value entered for the High Speed Warning value, the control will display a High Speed warning message. The input value for this High Speed Warning alarm must be equal to or less than the value entered for the High Speed Critical value. The lowest value allowed for this warning is equal to the Low Speed Warning value. To expand the allowable input range for the High Speed Warning value, the High Speed Critical and Low Speed Warning values may first need to be adjusted.

Current Speed

This value is the real time metering speed of the discharge system.

Low Speed Warning

If the Current Speed falls below the value entered for the Low Speed Warning, the control will display a Low Speed warning message. The input value for this Low Speed Warning alarm must be equal to or less than the value entered for the High Speed Warning value. The lowest value allowed for this warning is equal to the Low Speed Critical value. To expand the allowable input range for the Low Speed Warning value, the High Speed Warning and Low Speed Critical values may first need to be adjusted.

Low Speed Critical

If the Current Speed falls below the value entered for the Low Speed Critical, the dryer will shut down. The input value for this Low Speed Critical alarm must be equal to or lower than the value entered for the Low Speed Warning value. To expand the allowable input range for the Low Speed Critical value, the Low Speed Warning value may first need to be adjusted.

VFD Frequency = 6 Hz

VFD Frequency = 54 Hz

Depending on the model dryer, the % discharge speed will correspond to an approximate bu/hr or metric tonnes/hr value for a known discharge capacity. The table below correlates discharge speed % to bu/hr based for the moisture removal (5pt or 10pt) and mode of operation (All-Heat or Heat+Cool) stated above.

VFD Frequency = 42 Hz

VFD Frequency = 48 Hz

VFD Frequency = 18 Hz

AccuDry Status

While running in manual mode, AccuDry mode will not be available until the system is "Ready." The ready state is shown by the color of the AccuDry button, which is explained below.

The TruDry Settings page is very similar to the Manual Settings page. The only difference, other than the component quick launches, is the "Set Discharge Speed" box displayed on the Manual Settings page has been replaced by mid-grain temperature boxes.

To understand the settings on the TruDry Settings page, it is best to first have a good understanding of how TruDry works.

TruDry Technology

TruDry is the name of a temperature based discharge mode of operation that automatically increases or decreases the discharge speed of the dryer. TruDry is not an automatic moisture control mode of operation and does not utilize the discharge moisture value, but instead controls the discharge rate by attempting to maintain an average mid-grain temperature setpoint. The mid-grain temperature is the temperature of the grain, measured approximately halfway down the heat zone of the dryer, and halfway into the grain column by an RTD (resistive temperature device). There are two RTD's, on opposite sides of the dryer, measuring the grain temperature. These two temperatures are used to calculate the average mid-grain temperature. The principal of operation is that as the grain entering the dryer increases in moisture, the mid-grain temperature will go down and when the grain entering the dryer decreases in moisture, the mid-grain temperature will go up. Therefore, what the controller will do is utilize a negative responding Proportional-Integral-Derivative (PID) control loop which will increase the discharge rate when the mid-grain temperature goes up and decrease the discharge rate when the mid-grain temperature goes down. This essentially means that as the grain's moisture goes up, the dryer will slow down and as the grain's moisture goes down, the dryer will speed up.

Depending on the model dryer, the % discharge speed will correspond to an approximate bu/hr or metric tonnes/hr value for a known discharge capacity. The table below correlates discharge speed % to bu/hr based for the moisture removal (5pt or 10pt) and mode of operation (All-Heat or Heat+Cool) stated above.

VFD Frequency = 12 Hz

VFD Frequency = 24 Hz

VFD Frequency = 60 Hz

Depending on the model dryer, the % discharge speed will correspond to an approximate bu/hr or metric tonnes/hr value for a known discharge capacity. The table below correlates discharge speed % to bu/hr based for the moisture removal (5pt or 10pt) and mode of operation (All-Heat or Heat+Cool) stated above.

Depending on the model dryer, the % discharge speed will correspond to an approximate bu/hr or metric tonnes/hr value for a known discharge capacity. The table below correlates discharge speed % to bu/hr based for the moisture removal (5pt or 10pt) and mode of operation (All-Heat or Heat+Cool) stated above.