Installation Manual PA Pro III
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2018-03-16 Page 8 of 30
4
Connection of power measurement
Important!
Improper use of ClimaCheck power meters may cause high voltage
build up that can be dangerous both for equipment and operators. Adhere to the
practices below to avoid this:
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Always connect the CTs to the power meter before they are attached around a live
wire.
-
Always remove the CTs from the live wire before the cables to the power meter
are disconnected.
-
Incorrect connection of voltage between phase and neutral will damage the
equipment.
-
Never use the CTs on uninsulated wires or rails.
In addition, follow the steps below to assure proper power and energy readings:
-
It is important to only measure the power to the compressor. Make sure the measurement
is done after the point where circulation pumps and fans are connected.
-
Make sure that the voltage and current for each phase corresponds with the markings on
the measuring equipment and that the arrow on the current clamps are pointing in the
direction of the current.
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Make sure that the CTs are completely closed and that the contact areas are clean.
-
Check that the connections are correct by reading the voltage, current and power on the
display of the power meter. If you find a problem remove the clamps and attach L1
followed by a control and the repeat the process for L2 and L3.
4.1
Motor configurations
Power measurements require good understanding of the electrical layout of the plant.
It is for example necessary to identify if a three-phase motor is part winding or Y/D (Star/Delta)
and connect accordingly.
4.1.1
Part Winding
Part winding means that the motor has two separate windings and the total current to these should
be measured. This can be done in several ways depending on the physical restrictions of cables and
CTs.
-
Preferred choice is to measure before the contactors where the total current runs through
one lead. This can sometimes be physically impossible.
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One alternative is to put clamps around both L1 cables after the contactor or in the
connection box on the compressor if this can be done. This is repeated for L2 and L3.
-
It is possible to measure with 6 clamps i.e. 2 in parallel to the instrument per phase.
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If there is no way to connect around the total current an acceptable approximation can be
achieved by measuring on one of the contactors (the one with largest power draw is
preferred) and adjusting the power scale in the ClimaCheck software Input tab. The ratios
are typically 50/50 or 60/40 and can be deduced by moving the clamp back and forth.
4.1.2
Y/D (Star/Delta)
Motor with Y/D start should preferably be measured before supply is split between the three
contactors this normally consist of e.g. at L1, L2 and L3.
