E.3 Slope and Intercept ConversionSeveral drive parameters are available for monitoring purposes. These include FREQ OUTPUT (Point 3), SPEED (Point 5),CURRENT (Point 6), TORQUE (Point 7), POWER (Point 8), DRIVE TEMP (Point 9), KWH (Point 10), and RUN TIME(Point 12). These points can be unbundled for monitoring or used in various global control strategies.u Drive Controlled FeedbackThe most typical application is Supervisory Control. The sensor for the control variable (e.g., water temperature) is hard-wiredto the drive and the control device (fan) is modulated using the PI control loop that is built into the drive. The setpoint for thecontrol variable (water temperature setpoint) is unbundled and commanded by the field panel, based on some building controlstrategy implemented in PPCL.When this strategy is used, the point to unbundle and command for the setpoint is INPUT REF 1 (Point 60). The controlvariable (e.g., water temperature) can be monitored by unbundling PI FEEDBACK (Point 62). These points are provided inunits of percent, where 0% and 100% correspond to the range of the sensor being used to measure the control variable. Thesepoints have default units in Hz. If other units are required, unbundle these points with appropriate slopes and intercepts. Thenew intercept will be equal to the lowest value of the desired range. You can define a new slope and intercept using the formulabelow to convert the units:New Slope = (60 - 0)Hz x (0.01)(100 - 0)% = 0.006New Slope = (Desired Range) x (Slope of Existing Point)(Range of Existing Point)Conversion ExampleYou are controlling water temperature from a cooling tower using the drive to control a fan. The temperature sensor has arange of 30 °F to 250 °F. To unbundle the setpoint (INPUT REF 1), for commanding in degrees Fahrenheit, where 0 to 60 Hzis equal to 30 °F to 250 °F:New Intercept = 30 (the temperature that corresponds to 0%)New Slope = (250 - 30)°F x (0.1)(100 - 0)% = 0.0222New Slope = (Desired Range) x (Slope of Existing Point)(Range of Existing Point)Formula Notes:Desired Range = Range Maximum – Range MinimumRange of Existing Point = Existing Range Maximum – Existing Range Minimumu Field Panel Controlled FeedbackIn this strategy, the sensor is connected to the APOGEE FLN network at a remote location, and the control loop is executedin PPCL. The drive speed command is passed from the field panel to the drive by commanding INPUT REF 1 (Point 60).NOTICE: This strategy is not recommended because the loop is being closed over the network. Delays from processor scan time andnetwork traffic can cause degradation or loss of control. Damage to HVAC equipment may result.Unbundle the FEEDBACKTo unbundle the feedback (PI FEEDBACK) for monitoring in degrees Fahrenheit:New Intercept = 30New Slope = (250 - 30)°F x (0.1)(100 - 0)% = 0.0222New Slope = (Desired Range) x (Slope of Existing Point)(Range of Existing Point)Formula Notes:Desired Range = Range Maximum – Range MinimumRange of Existing Point = Existing Range Maximum – Existing Range MinimumE.3 Slope and Intercept ConversionYASKAWA ELECTRIC SIEP YAIZ1B 01E YASKAWA AC Drive – Z1000 Bypass Technical Manual 411E Apogee FLN NetworkProtocol
