Schneider Electric Multi-Loader Dokumentacja Pobierz pdf (Strona 37)

Functions (continued)

Altivar

variable speed drives

Pump-specic application functions

Themainobjectivehereistocontrolacompletepumpinginstallationusingasingle

Altivar

12drivebyensuringconstantpressureinthesystemwhatevertheowrate.

The Altivar 12 has 11 functions designed for water pumping applications:

b Control in single variable mode

b Control in single variable mode with auxiliary pump

b Underload detection

b Overload detection

b Sleep

b Wake-up

b PID feedback supervision

b No-load operation detection

b Quick start

b Automatic restart on underload and overload faults

b PIDreferenceadjustmentrangefortheenduser

Control in single variable mode

The system is operated using a single variable speed pump (

A PID regulator controls the variable speed pump.

A pressure sensor provides the “PID feedback” information required for system

feedback.

Control in single variable mode with auxiliary pump

Thesystemisoperatedusingaxedspeedpump,calledtheauxiliarypump,anda

variablespeedpump,whichisunabletoprovidethefullowrangerequiredonits

own (

The auxiliary pump's starting and stopping are controlled by logic output LO+

according to the PID regulator output (variable pump frequency reference) with a

hysteresis effect as shown in the diagram below (

Auxiliary pump starting (

)

If the variable pump control frequency exceeds the threshold (FOn) for longer than a

time period (tON), the auxiliary pump is put into operation (1). The variable pump

reference decreases linearly until it reaches the threshold (FOF).

In order to reduce the effect of overpressure caused by starting of the auxiliary

pump, the deceleration time of the variable pump (rOn) must be set to the time that

the auxiliary pump takes to reach its nominal speed.

Auxiliary pump stopping (

)

Conversely, if the variable pump control frequency falls below the threshold (FOF)

for a period (tOF), the auxiliary pump is stopped (2) and the variable pump reference

increases linearly until it reaches the threshold (FOn). The acceleration time (rOF)

is set to the stopping time of the auxiliary pump in order to minimize the effect of

underpressure.

FOF

FOn

HSP

Single variable mode with auxiliary pump: hysteresis

Installationowrate

Variable pump frequency (Hz)

FOF

FOn

tOn rOn

Auxiliary pump start

Variable pump frequency (Hz)

FOF

FOn

tOF

rOF

Auxiliary pump stop

Variable pump frequency (Hz)

Auxiliary pump starting1

Auxiliary pump stopping2

Frequencyrangecorrespondingtotheauxiliarypumpowrate3

FOn: Starting frequency of the auxiliary pump

FOF: Stopping frequency of the auxiliary pump

Introduction:

page 8

Specications:

page 10

References:

page 14

Dimensions:

page 18

Connections:

page 22

Single variable mode

Single variable mode with auxiliary pump

Courtesy of Steven Engineering, Inc.-230 Ryan Way, South San Francisco, CA 94080-6370-Main Office: (650) 588-9200-Outside Local Area: (800) 258-9200-www.stevenengineering.com

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