Bell & Gossett P2001489 Integrated Technologic with Sensorless Control - Manual (Page 33)

If the controller is configured to operate with a wired sensor or in sensorless flow control
mode, additional parameters must be set to properly configure the flow compensation
function because pump performance data is unknown by the controller. In a sensorless
application the controller is preprogrammed with the pump performance data. This
means that only 3 points (setpoint, pressure at no flow and flow at design point) are
required to determine the control curve for a sensorless application. For a sensorless flow
or wired sensor application the pump data is not known so additional parameters must be
configured for proper operation of the flow compensation function. The parameters that
are required to be configured will depend on whether the speed at the design point is
known. If the speed at the design point is known, set Work Point Calculation (parameter
22-82) to disabled. Set the Speed at No Flow [Hz] and Pressure at No-Flow Speed
(parameters 22-84 and 22-87 respectively), which correlate to point A on the diagram
below. The intersection of the system setpoint and Speed at Design Point [Hz] (parameter
22-86) correlates with point B. With this information the controller can then calculate the
control curve. Refer to the diagram below.
Figure 17: Flow compensation with sensorless control disabled and speed at system design
working point is unknown
Table 11: Flow compensation parameters when speed at design point is known
Parameter number Description Set to
22–80 Flow compensation Enabled
22–81 Square-Linear-Curve approximation Modify between 100% (square) and 0%
(linear) per system requirements.
22–82 Work point calculation Disabled
22–84 Speed at no flow (Hz) To find this point, close all valves in the system
and run the pump at the minimum design
head. The speed corresponding to the
minimum head requirement at no flow will be
entered here.
22–86 Speed at design point (Hz) These points correspond to the speed required
to maintain point B (design head (setpoint)
and flow).
22–87 Pressure at no flow System pressure at no flow and no flow speed.
This is the minimum design head.
If the speed at the design point is unknown, the Work Point Calculation (parameter 22-82)
must be enabled. With the Work Point Calculation enabled the controller will calculate the
speed at the design point based on settings of some additional parameters correlating to
the points shown on the diagram below. The first point determined is point A which is the
minimum required head at minimum speed (parameters 22-84 and 22-87). Points C and D
can be determined by consulting the pump performance curve. Point C is determined by
extending the design setpoint line horizontally to intersect the rated curve which is the
pump performance curve at rated speed (usually 50 or 60Hz). The flow at this point
(Q
Rated
) is set in parameter 22-90 Flow at Rated Speed. Point D is determined by
extending the design flow point (Q
Design
) vertically to intersect the rated speed curve. The
System Setup and Operation
Integrated Technologic ® with Sensorless Control INSTRUCTION MANUAL 31