Schneider Electric ALTIVAR 58 TRX - Manual (Page 29)

Altivar ® 58 TRX AC Drives
I/O Extension Cards
29
09/2003 © 2000–2003 Schneider Electric All Rights Reserved
Pump Switching Option Card (VW3A58210U)
The pump switching option card can control a complete pumping installation
using a single ATV58 TRX drive controller. It provides:
• Constant pressure in the system whatever the flow rate
• A simple method for installing and diagnosing the installation using the
ATV58 TRX drive controller
The pump switching option card can operate up to four fixed speed pumps
and one variable speed pump (the variable speed pump cannot provide the
full flow range required on its own). A PI regulator is used for drive control and
a pressure sensor is required to provide system feedback.
To prevent uneven wear of the pumps, the card allows pump switching
according to operating time. The variable speed pump can be included in the
swapping procedure.
Application Example (with 3 auxiliary pumps and one variable pump)
In this example, the auxiliary pumps are switched on and off according to the
flow rate required by the installation. The variable pump is controlled to
compensate for any flow rate variations.
The ATV58 drive controller controls the pumps via logic outputs DO1, DO2,
DO3 etc., depending on the operating mode programmed.
The logic inputs indicate the state of the pumps.
• If LI = 1, the pump is ready to start and used in the automatic sequencing.
• If LI = 0, the pump is not ready and will not be used in the automatic
sequencing.
Internal elapsed timers are used to keep track of the accumulated operating
time of each pump.
2 3 1 0
P3
P2 P2
P1 P1 P1
PV
PV
PV
PV
4
P1 M1 P2 M2 P3 M3 PV M ATV58
Control of auxiliary pumps
VW3A58210
card
Number of pumps required
Flow rate
demand
PV: variable pump
P1, P2, P3: auxiliary pumps
M, M1, M2, M3: motors
Flow rate at
constant
pressure
Pressure
measurement
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