ABB PSTX Series Installation And Commissioning Manual page 126

7.21 Pump cleaning
Pump cleaning function makes the pump motor alternate
between forward and reverse direction. This sequence
can release or cut through solid objects and flush away
effluent.
The pump cleaning function can be used to solve these
two problems which are common especially in waste
water plants.
• Jamming: Occurs when a semi large solid object like
a piece of plastic or wood gets stuck in the pump
blades.
• Clogging: When the liquid that is being pumped
contains small particles and effluent, the risk is that
this material will over time get permanently attached
within the pipes and cause water flow problems which
will decrease the pump efficiency and can damage the
pump.
Solving these problems will result in an overall improved
pump efficiency, reduced down time and low maintenance
costs.
To detect when a pump is jammed or clogged, it's
recommended to use one of the following methods.
• When an object is stuck in the pump, the motor
7
uses more current and the Softstarter will trip on
EOL (Electronic Overload), see chapter 7.17.1 EOL
Protection or Locked rotor protection, see chapter
7.17.2 Locked rotor protection.
• During a soft start the Too long starting time, see
chapter 7.17.18 Too long start time protection,
or Too long time at current limit, see chapter 7.17.17
Too long current limit protection, can be used to
indicate that an object is stuck in the pump.
• A water flow sensor can be used to detect if the pipes
are clogged. The sensor output can be connected to
one of the PSTX programmable inputs and configure it
as user defined protection, see chapter 7.17.15 User
defined protection
INFORMATION
The Softstarter cannot automatically start the
pump cleaning sequence when the fault events
mentioned above occur. External logic have to be
used to give the pump cleaning commands if and
when the protection events occur.
Pump cleaning can also be used as preventive
maintenance by running the function once a day/
week.
126 Functions | Installation and commissioning manual | 1SFC132081M0201