DBB22000 ABB, DBB22000 Datasheet - Page 15

• Manufacturer Part Number: DBB22000
• Description: ENERGY METER 3P+N 80A DIRECT CLASS A
• Manufacturer: ABB

Specifications of DBB22000

• Current Rating: 80A
• Rohs Compliant: Yes
• Svhc: No SVHC (20-Jun-2011)

Introduction
In most cases, the three-watt meter method is used for
power measurements in three phase systems with a
current-carrying neutral conductor. Where metering is
the basis for billing, this is a requirement.
High voltage installations often do not have any current-carrying
neutral conductor, therefore the two-watt meter
measurement method can be used. Both voltage and
current transformers are commonly used. Single phase
metering can be used if a three-phase load is balanced.
If the DELTAplus meter is directly connected to the mains, the
device must be protected by fuses (the possibility to isolate
the meter is recommended) on the incoming side.
In order to allow maintenance of DELTAplus Meters with current
transformers connected, a short circuiting terminal
block should be installed near the meter. The voltage
supply to the meter must be protected by a max. 10A
fuse.
Active and Reactive Power
Active power is needed to perform work. However, consumer
equipment often cause a phase shift between
current and voltage as a result of the inductive nature of
the load, for example in motor drives. The maximum
permissable phase shift is governed by the terms of the
consumers’ contract with the electricity supplier. If the
consumers exceed the specified maximum, they will be
liable to an extra charge and would be well advised to
install compensation equipment, usually in the form of
capacitor banks. Thus it can be seen that the reactive
component of the power also is of interest for measurement.
Resistive loads cause no phase shifts.
Inductive loads cause a phase shift in one direction,
while capacitive loads produce a phase shift in the
opposite direction. As a result, inductive and capacitive
loads can be used to compensate each other. The
phase shift of the current compared to the voltage
results in the power being divided into active and reactive
components. The angle between the actual power
vector and the active power component is described as
phase displacement angle, often referred to as .
ABB
Resistive
load
Capacitive
load
DELTAplus
Electricity Metering
Inductive
load
Methods of Measuring Power
The single-watt meter method (single phase)
In three phase systems the single-watt meter method
only gives correct results with a symetrical load on the
phases. Since in practice perfectly balanced systems
are very rare, this method should not be used for accurate
measurements.
The two-watt meter method
The two-watt meter method is used in three phase systems
without a neutral conductor, irrespective of the
load symetrical or asymetrical.
The three-watt meter method
The three watt-meter method is usually used in three
phase systems having a neutral conductor. This method
can deal with asymetrical and symetrical loads.
P= 3 x I
T
x U
T
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