Yaskawa iQpump Controller Programming Manual - Manual (Page 227)

YASKAWA TM.iQp.07 iQpump Controller Programming Manual 227
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Basic Concept
When this feature is enabled, the drive will still use the standard iQpump PI controller to control pressure. If the water in the well drops to
the Water Level Setpoint (P8-03), the drive will seamlessly switch over and control water level instead using an additional PI controller.
Under most circumstances this will cause a reduction in flow rate and pressure, as the drive is then attempting to match the output of the
pump to the rate that water is recharging the well. If the pressure returns to the pressure Setpoint at any time, the drive will seamlessly
switch back to controlling pressure.
If the well level drops below the Minimum Water Level (P8-04) for more than the Sleep Delay Time (P2-03), the drive will go to sleep.
The drive will resume operation when the level in the well goes above the Wake-Up Level (P8-05) for more than the Start Level Delay
Time (P1-05).
There is a water level detection feature as well. If the water level drops below the Low Level Detection Level (P8-07) for more than the
Low Level Detection Time (P8-08), the drive will respond depending on the setting of the Low Level Behavior (P8-09) parameter. This
feature is also active in “Hand” mode.
The drive will NOT perform a sleep boost if it is being forced to sleep based on the water level.
■ Function Description
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Enabling Level Control Features
The level control features, pressure and level control plus Low Level Detection can be enabled by setting parameter P8-01 to 1 (Enabled).
The drive will only perform the pressure and level control when “normal” PI mode is enabled
(b5-01 > 0, not jogging, not disabled via MFDI, etc.), and drive is not in a multiplex mode (P1-01 > 0).
Sensing Water Level
Terminal A1 will act as the water level analog input. An analog pressure sensor, mounted down in the well at the pump will provide the
required signal. Parameter P8-02 should be set to the full-scale pressure of the transducer. The drive will then convert the reported
pressure into an amount of water above the pump. (2.308966 ft / psi) This level will be displayed on the U1-98 monitor.
Wire break will be detected on Terminal A1 when:
• PI Feedback Loss Detection is enabled (b5-12 = 1 or 2)
• Pressure and Level control is enabled (P8-01 = 1)
• PI is NOT disabled via Multi-Function Digital Input
• Signal on Terminal A1 goes below -6.25% or above 106.25% for more than 1 second
Note: Wire-break detection on Terminal A1 occurs after the gain / bias parameters (H3-02 and H3-03) are applied.
The drive will then react depending on how parameter b5-12 is programmed.
Note: To convert Terminal A1 to 4-20 mA signal, connect a 250 Ohm precision resistor (1/4 Watt or greater) between A1 and
AC. Then program H3-02 = 231.2% and H3-03 = 25.0%.
Pressure and Level Control
When there is adequate water available in the well, the drive will regulate pressure using virtually all of the standard iQpump features,
including but not limited to: sleep, sleep boost, minimum pump speed, thrust bearing, pre-charge, utility delay, etc.
The drive can respond in one of two ways to a drop in water level inside of the well. If the Water Level Setpoint (P8-03) is programmed
to a value greater than the Minimum Water Level (P8-04), the drive will attempt to regulate the water level in the well to the P8-03 level.
As the water level approaches the P8-03 level, the drive will slow down which will cause pressure and flow will also decrease. The drive
will then regulate output speed in order to maintain the level in the well. The response of the drive when regulating level can be adjusted
using parameters P8-10 and P8-11. However, if the level in the well drops below the Minimum Water Level (P8-04), for more than the
Sleep Delay Time (P2-03), the drive will go to sleep. When the water recharges the well to above the P8-05 level for more than the P1-05
time, normal operation (pressure regulation) will resume.
Note: The Level Control Minimum Speed parameter (P8-06) should be set to a high enough value to insure flow.
The other way that the drive can respond is to try and maintain the pressure setpoint, then go to sleep immediately based on water level.
This can be accomplished by programming the Water Level Setpoint (P8-03) to a value less than the Minimum Water Level (P8-04).
When the level in the well drops below the Minimum Water Level (P8-04), for more than the Sleep Delay Time (P2-03), the drive will go
to sleep. When the water recharges the well to above the P8-05 level for more than the P1-05 time, normal operation (pressure regulation)
will resume.
Sleep and Wake-Up Methods
The drive will go to sleep in one of two ways. As described above, if the actual water level drops below the Minimum Water Level (P8-
04) for more than the Sleep Delay Time (P2-03), the drive will go to sleep without performing a sleep boost. The drive can also go to