Adveco EB0025, Руководство по эксплуатации продукта

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Components & Terminology
Normally Open and Normally Closed
This refers to the switches within the electrical switchgear. The designation of NO/NC is always given
with the component in its de-energised or off state. This can make reading electrical schematics difficult because
components that are usually closed are shown open. A circuit breaker is a switch that is normally open (off) but
usually open when the system is operating. To properly troubleshoot and understand the drawings, this must be
understood.
Circuit Breaker
Circuit breakers provide over-current protection for the components of the hot water system. They can
be single breakers for single-phase components, or in blocks of three for three-phase components. The ratings
of the included circuit breakers have been chosen to provide the correct level of protection.
Circuit Breaker Auxiliary
An auxiliary is an electrical switch mechanically fastened to the circuit breaker. It has a normally open
and normally closed switch. When the circuit breaker trips the auxiliary changes state.
Contactor
A contactor is a three-phase high current switch which is activated by an electromagnet. When a low
voltage / low current is provided to the coil of the contactor between A1/A2 the current in the coil creates an
electromagnet which changes the state of the switch. This is how a small, single-phase thermostat can turn on a
large three-phase immersion heater. The main contacts can be NO or NC and auxiliaries can be included to
switch multiple signals. There is a test button in the centre of the contactor to test the contacts.
Relay
A relay is effectively a single-phase contactor. It has a coil to create an electromagnet to switch the
state of the device, as well as a series of NO/NC contacts that can be used independently of each other. It is
used to switch a component on/off without the voltage and current of the component passing through the
switching device; it is also used for out of sequence switching (when the controlling device turns off, the
component turns on).
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EB0025-EB0028-EB0030 Control Panel - Installation and maintenance manual