Data Sheet for Product

2
Siemens
023_A6V11905989_en
2022-01-
07
Application
The heat (WSM8..), cooling (WSB8) and combined heat/cooling energy meters (WSN5..) are
measuring devices to physically acquire energy consumption. The devices consist of a flow
measuring section and processor unit. The processor unit can be equipped with various
sensors, different types of power supply and communication modules.
WSx8.. meters are employed to measure heat consumption and are also suitable for
measuring cooling (alone or combined with thermal energy) in systems with water.
Restrictions
Do not use the WSx8.. to measure potable water.
They are not suited for use in systems operating on water-glycol mixtures.
Functions
Meter design
The meter consists of an electronic unit, flow measuring section, and 2 temperature sensors.
The processor can be equipped with up to four long-term batteries to operate up to 20 years.
Ultrasonic measuring principle
The flow is acquired based on the non-wear ultrasonic measuring principle, which requires
no moving parts.
The amount of energy transferred from the medium to the consumer over a defined period of
time is proportional to the temperature difference between the warmer and colder side and
the volume of water that has passed through.
The water volume is measured in the measuring tube by ultrasonic pulses which are
transmitted in the direction of flow and against the direction of flow. Downstream, the time
difference between the transmitter and receiver is reduced, upstream it is increased. The
water volume is calculated based on the difference in runtime.
The flow and return temperature is acquired by platinum resistors.
The water volume as well as the temperature difference between the warmer and cooler side
is multiplied using a heat coefficient and the product is integrated. The result, which is the
consumed amount of thermal or cooling energy, is registered and displayed in the physical
unit kWh or other common unit, the volume in m
3
.
The WSx8.. uses an intelligent, adaptive temperature-measuring interval. With changing
system conditions (e.g. rapid increase of flow), the WSx8.. changes for a certain time to a
fast temperature-measuring interval. In other words, the meter always adapts to the current
situation and acquires the system temperatures very accurately.
In addition to heat energy, the meters measure cooling energy as an option that is added to
a separate tariff register (uncalibrated). Heat energy is always measured if the temperature
difference (>+0.2 K) and the flow is positive. Cooling energy is measured, if the
temperature difference (<-0.2 K) is negative, while the flow is positive.
Processor unit
A common electronic unit applies to all flow variables.
Removable temperature sensor
Temperature sensor can be exchanged on the meters.
It must be individually calibrated or compliance certified when using temperature sensors.
The maximum allowable cable length of the temperature sensors is 10 m (default 1.5 m).
Further extensions are not permitted.