Dynamic Speed De-Rate

Overview

A new feature with DCT version 1.55.59 and Brain version 2396 is the dynamic speed de-rate, which allows to specify a sensor condition that will clamp the top speed of the unit to some value. This can be used, for example, to lower the top speed when the intake temp is too high and speed back up again when back low.

Setup

 The feature is set up at Settings - Brain - Outputs Setup - Dynamic Speed De-Rate.

This page has three settings:

• Condition: Specify a condition to enter a de-rate. The condition can be based off any Brain analog input or thermocouple, or a few engine sensors like intake manifold temp, oil temp, coolant temp, and a few others. The engine sensors can come from an EMIT ECU or the ADEM(r) via the EDT - but make sure the value actually shows up on the EDT home page first to verify it is being collected correctly.
• Deadband: This value specifies the offset to the condition to re-enter running speed. In the above screenshot example, since the derate begins when manifold temp is above 150, since the deadband is 10 the de-rate will end when manifold temp goes below 140. This adds a gap between the start and end to prevent constantly cycling between de-rated and normal speed.
• Max speed when de-rated: This gives the new max speed when the de-rate is active. The speed won't be allowed above this RPM whether in Auto or Manual.

De-Rate Process

Once the De-Rate condition becomes active the speed will be clamped to the new specified max speed. If the unit is not already running above that speed then there will be no change. If the unit is running above that speed it will ramp down to the new de-rate speed.

While de-rated, the auto and manual still work normally other than the new maximum speed. In manual the engine can still be slowed down and sped up with the +/- switch, but not above the de-rate speed. In auto, the unit can still run off a sensor control (e.g. suction), but won't be allowed above the de-rate speed.

Once de-rate ends the max clamp goes away and normal operation resumes. If in "Auto" then the speed may ramp up again if set to fixed speed or if sensor control calls for it. Note that in Manual mode the speed won't change after exiting de-rate, it will simply now be allowed to go to a higher speed again. For this reason, if using de-rate and intending to have the unit speed back up automatically then the Auto switch position should be used.

Example

Setup:

• De-rate when intake manifold temp is above 150
• Deadband 10
• Max speed when de-rated 1200
• Auto speed setup: Fixed speed at 1500

The unit will run at 1500 RPM if in the "Auto" switch position. When the manifold temp goes above 150, the speed will ramp down to 1200 (the de-rate speed). At some point in the future if the manifold temp goes below 140 the unit will speed back up to 1500 RPM (the auto speed).

Status

The speed control status gauge (if used) and the speed control status under "Brain State" -> "Speed Control" will both show if a de-rate is active.

Gauge example when de-rate is active