Download L2 - start level for the second pump

TECHNICAL RAPORT
Motor protection, automation, local data display, data acquisition
and transmission - Dispatching -
The 10 Wastewater Pumping Stations in Eforie Sud (Agigea, Steaua de
Mare, I.T.T.A., C.F.R. Bridge, T.B.C., Tuzla, Techirghiol, Schitu, Costinesti,
“Students Camp” and “Pioneers Camp”) use n submersible pumps noted - P1, P2,
P3 …Pn . Electrical pumps are chosen so that the maximum required output flow
should be supplied by m of them, the others being kept as stand-by. Stand-by
pumps are to insure the functionality of the system in case of system damage or
during maintenance or repairing operations.
The functioning sequence of the pumps depends on the water level in the
sump. Thus, the height of the sump is divided into m+1 levels, meaning:
L0
L1
L2
- stop level for all pumps
- start level for the first pump
- start level for the second pump
Lm
Lm+1
- start level for the “m” pump
- alarm level (when the stand-by pumps, if
available, must be activated).
Initially, when the sump is almost empty, and the water has not yet reached
the L1 level, none of the pumps works. If level L1 is attained, the P1 pump is
activated. Should the evacuation debit insured by P1 leads to the decrease of water
level in the sump, the pump continues to work until level L0 is reached, and then it
stops. Should the input flow be higher than the P1 evacuation capacity and the
level of the water increase further, when the L2 level is attained the P2 pump is
started. Both P2 and P3 will continue to operate until the sump is empty, when the
water will be under L0 level. The process repeats identically for the other pumps
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too. L0 is a bit higher than the floor level of the sump, in order to avoid the dry
functioning of pumps. (without water).
Should the functioning time on one pump only (for which the water level of
the sump is between L1 and L2) after a certain amount of time, i.e. 3 hours, the
pump will be stopped and will be waiting for the water to reach L2 level in order
to safeguard the self-cleaning speed of the waste pipes on the Pumping Stations at
I.T.T.A., Costinesti Pioneers and C.F.R. Bridge. After that, the initial functioning
algorithm will then be reinstated.
If, accidentally, the system’s evacuation capacity is less than the input flow
and the water reaches the maximum admitted level, Lm+1, the automation module,
BAM, commands the functioning of the stand-by available pump (pumps) and
activates both acoustic and visual alarm, warning the user that overflow is
imminent. Input from the level transducer or sensors and the alarm start command
go through MAC acquisition and command module. The same module shows the
output flow and the state of the grid on/off/ failed.
To detect L1, L2,…Lm+1 levels, switch floats can be used, specially designed
to resist the aggressive environment in which they are functioning. Due to the
material they are covered with (prolipropihlena), and also to their bulbous form,
they reject any solid or fat deposits on their surface, thus, not requiring periodical
cleaning. They are designed to be resilient to a large scale of temperature and
impurities concentration, inherent to the exploitation of the system. As an
alternative choice, for detecting the level of the sump, level transducers
(submersible pressure sensor or ultrasonic) can be used.
To insure the uniform use of the pumps (duty and stand-by) and for wear
equalization, BAM measures the functioning time of each and activates first the
ones that have operated for a shorter time.
A submersible mixer is used to avoid mud deposits to crust on the floor of
the sump and for preventing the sedimentary effects. The mixer activation will be
automatically commanded by BAM, during the period pumps do not work, or
when the water level of the sump is between the limits of L1 and L2 levels or
manually, from the local panel.
To force the evacuation of the noxious from the collecting sump and also
from the inside of the pumping station, ventilation devices are used. These are
programmed to function regularly, at moments dictated by the BAM module, and
coordinated through MAC acquisition and command module. Before any
intervention, the ventilation devices can be tuned on and off by the operator
locally or from the dispatcher, bypassing the auto sequence.
Should an accidental break down of the power supply network, a certain
number of pumps shall be started, depending on the current water level from the
sump. In this case the BAM module will command the sequential start of the
pumps (within given settings), thus avoiding the occurrence of current peaks
which could affect both the power line and the transformer. The stop pumps will
similarly be done sequentially, within given settings.
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BAM also controls the restarting number per hour for each pump so that
this number shouldn’t be higher than the producer’s recommendations.
An electrovalve will be installed on each pipe. The BAM module will
command the electrovalves so that their closing will occur before the starting of
the pumps and they will be opened after the starting of the pumps. The operator
(locally or by the dispatcher) will be able to program through the BAM the
opening degree for the open the close position.
The control panel insures the protection of the pumps, mixer, electrovalves
and ventilation devices. Thus, to increase both the functioning safety and the
pumping system efficiency, protection and command multifunctional relays MPC
are used.
MPC equipment safeguards individually for each pump and mixer from the
following usual cases of failure:
Voltage protection:
- reversal of phase rotation
- phase failure
- under voltage
- over voltage
- voltage unbalance
Current protection:
- current phase failure
- undercurrent (idle running)
- short-circuit
- difficult motor starting
- locked motor
- current unbalance
Special protection:
- insulation fault (not for the mixer)
- over temperature bearing
- over temperature in the stator coils
- leakage water in oil
- water in the stator housing
- leakage water in junction box
- dewatering.
The detection of any of the above mentioned malfunctions causes the motor
to stop. Restarting may be attempted either automatically or manually. The motor
cannot be restarted unless normal operating conditions are reached (power supply,
insulation, temperature, humidity and water level) whether manually or
automatically. MPC has independent keyboards and displays, which makes
possible to program the working data, to check technological parameters and the
type of failure. Both programmed parameters and the types of failure detected,
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together with the time and date of occurrence are recorded in an nonvolatile
memory. Aside from the types of failure detected together with the time and date
of occurrence, MPC equipment will display the following data for each pump and
mixer:
- phase currents
- phase voltages
- total operation time.
Protection and command of the electrovalves will be insured by the MPV
device that will protect them against the following failures:
- reversal of phase rotation
- phase failure
- under voltage
- over voltage
- current phase failure
- short-circuit
- overload
- motor torque exceed
- over temperature
MPV will also allow the local open – close command of the electrovalve,
local display and degree of electrovalve opening for both extreme positions,
condition check of the electrovalve (open – close – damaged) as well as the type
of detected failure.
All detected malfunctions of pump, mixer, ventilation devices and grid
status parameters together with possible failures on the internal communication
network (that insure data and commands transfer between BAM and MPC or
MAC module) are surveyed with the help of a special displaying device – MAF.
These are installed in front of the electrical panel and centralise all global and
individual data corresponding to installed protection and command and
acquisition and command equipment. Thus MAF displays additional information
as follows:
- the state of pumps, ventilation devices, mixer and grid (on – off –
failed)
- the state of electrovalves (opened – closed – failed)
- the type of detected failures
- valve position for open and close
- the current water level
- the current output flow
- phase voltage for each phase
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- power supply frequency
- currents for each phase
- total operation time
- phase shift between current and voltage on each phase (for pumps)
- motor insulation resistance (for pumps)
- active power (for pumps)
- reactive power (for pumps)
- power factor (for pumps)
- active energy (for pumps)
- reactive energy (for pumps)
All electrical and non-electrical parameters of the pumping system,
including the programmed values of the various devices comprising it, are
transmitted via a MR modem and a SR radio station to a dispatching station.
Thus the dispatching station controls totally and uninterruptedly any of the
installed devices of the pumping stations with the help of the regulating
programme.
Installed automation and data transmittal equipment must be functional
even in case of voltage failure of the power supply network. In this case the
dispatching operator will be notified about failure or burglary detection. Data
feed will be insured by radio for the dispatcher and every pumping station with
the installation of modems and radio stations. The PC- mounted survey
program is part of the SCADA programs family (Supervisory Control and Data
Acquisition). It is conceived so that through the data transfer protocol it will
verify the correctness of the data and to insure the integrity of the transferred
information within the network. The program operates under Windows; it is
user friendly and easily installable. It shows the pumping stations on the zone
map. Upon selecting one of the stations, the program presents its detailed
localisation and technological chart, monitoring the water level in the sump and
the current state (on – off – unavailable) of the pumps, mixer, electrovalves,
and grids. It also acquires electrical, energetically and technological parameters
and displays then on request. Main features of the survey program:
Notifying the dispatcher upon failure or burglary detection:
Functioning failures detected by the protection and command equipment
corresponding to pumps, mixer, electrovalves, and grids are sent from the
stations to the dispatcher via the used communication channel. Types of failure
detected are displayed and stored together with the date and hour of occurrence.
The operator is compelled to confirm the received event; the time and date of
the confirmation are also stored for future reference. The activation of burglary
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sensors (upon unauthorized ingress) is interpreted as malfunctioning and the
dispatcher is instantaneously informed (remote by exception).
Inspection of pump, electrovalves and mixer operating parameters:
Upon command from the operator or in automatic supervision
(programmed time intervals), the dispatching station inspects the physical
values collected by the acquisition and control and protection and control
equipment. The values inspected are displayed on the operator’s screen and
stored. Thus, the data may be of further use for the generation of reports.
Automatic updating of data bases and report generating:
All detected failures collected technological parameters and configuration
data for protection and command or acquisition and command devices are
stored and they can be easily accessed. Individual or global reports on
malfunction in a certain time interval or the acquired physical values can be
generated, based on stored data and information.
Modification of MPC and MAC programmable parameters from the
dispatcher station:
From the dispatching point all configuration parameters for protection and
command and acquisition and command installed devices can be read and
modified. Each pump motor, mixer, electrovalve or ventilating device can be
individually started or stopped from the dispatching point or the current date or
hour of the clock with which the MAC and MPC are provided may be updated
here as well.
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