English
8
WILO SE 12/2020
Fault-actuated switchover of multi-pump
system
Switchgears with frequency converter – CC-FC
version:
If the base-load pump has a fault, it is switched off
and another pump is switched onto the frequency
converter. If the frequency converter has a fault,
the switchgear switches to "auto without fre
-
quency converter" operating mode with the asso
-
ciated control characteristics.
Switchgears without frequency converter –
CC version:
If the base-load pump has a fault, it is switched off
and one of the peak-load pumps is managed by
the switchgear as a base-load pump.
Switchgears in the CCe version:
If the base-load pump has a fault, it is switched off
and another pump takes over the control function.
As a result of a fault of the peak-load pump, it is
always switched off and a further peak-load pump
(if necessary, also the standby pump).
Low water
A low water signal can be sent to the switchgear
via a normally closed contact based on the signal
from a suction-side pressure switch, break tank
float switch or optional level relay.
Monitoring of maximum and minimum pressure
Limit values for safe system operation can be set.
Ext. Off
It is possible to deactivate the switchgear exter
-
nally using a normally closed contact. This func
-
tion takes precedence; all pumps are deactivated.
Operation in the event of a sensor fault
In the event of a sensor fault (e.g. wire break), the
behaviour of the switchgear can be defined.
Operating mode of the pumps
The operating mode of the respective pump can
be specified with the PLC (manual, off, auto) dur
-
ing activation.
Emergency operation
In the event of the control failing, there is the
option to commission the pumps individually by
means of the manual-0-auto switch (Fig. 1a-e;
item 8) on the mains (or per manual control with
individually settable speed for each pump – only
CCe version). This function takes precedence over
pump activation by the control.
Setpoint changeover
The switchgear can work with 3 different set
-
points.
Remote setpoint adjustment
Remote adjustment of the setpoint is possible
using an analogue current signal (optional voltage
signal) by means of the corresponding terminals
(acc. to circuit diagram).
Constant speed
Constant speed mode is possible via an analogue
current signal (optional voltage signal) using the
corresponding terminals (according to circuit
diagram).
Logic reversal of the collective fault signal (SSM)
The required logic of the SSM can be set.
Function of the collective run signal (SBM)
The required function of the SBM can be set.
Fieldbus connection
The switchgear is prepared for connection
via ModBus TCP as standard. Connection is estab
-
lished via an Ethernet interface (electrical connec
-
tion as per chapter 7.2).
The switchgear works as a Modbus slave. Basic
settings are adjusted on the user interface.
Different parameters can be read and also
changed to some extent via the Modbus interface.
An overview of individual parameters and a
description of the data types used are shown in
the appendix.
Pipe filling
The pipe filling function can be activated to avoid
pressure peaks when filling empty pipelines or
pipelines under low pressure.
6.2.2 Motor protection
Excess temperature protection
Motors with an WSK (thermal winding contact)
signal an excess winding temperature to the
switchgear by opening a bimetal strip contact. The
connection of the WSK is carried out according to
the circuit diagram.
Faults on motors that are equipped with a tem
-
perature-dependent resistor (PTC) for excess
temperature protection can be detected using
optional evaluation relays.
Excess current protection
Motors on switchgears up to and including 4.0 kW
are protected by motor protection switches with
thermal and electromagnetic trip triggers. The
trigger current must be set directly.
Motors on switchgears from 5.5 kW are protected
by thermal motor protection relays. These are
installed directly on the motor protections. The
trigger current must be set and is 0.58 * I
nom
with
the Y-∆ starting of the pumps used.
All motor protection devices protect the motor
during operation with the frequency converter or
in mains operation. Pump faults which reach the
switchgear result in deactivation of the corre
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