Verschildrukregelaar | -125 tot 125 Pa | PoM voeding

€ 154,61

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40sinds 10 jan. '25, 08:40

Beschrijving

The HPSPM-LP are differential pressure controllers for a range of -125 to 125 Pa. They are powered via the PoM system from sentera: Data and power supply via one cable and RJ45 connection. The integrated PI control with anti-windup function offers the possibility to control EC motors/fans directly. They are equipped with a fully digital, high-resolution sensor element. Zero point calibration and reset of the Modbus registers can be performed via a microswitch. All parameters are accessible via Modbus RTU.

What is the difference between a differential pressure sensor (or transmitter) and a differential pressure regulator?
The output signal of a differential pressure sensor (or transmitter) increases proportionally within the set range. So at a differential pressure of 0 Pascal the output is 0 Volt, and at 125 Pascal the output is 10 Volt.
If it were CO2 or relative humidity, it would be perfectly possible to control the speed of a fan or the position of a valve in this way: The more CO2, the more ventilation. Or the more moisture, the further the exhaust valve opens.
However, if it is differential pressure, it is unlikely that proportional control is used. Usually, pressure control does not work within a range, but rather at a set value, a "set point". A differential pressure regulator will then continuously adjust a fan, in such a way that the desired pressure - the set set point - is maintained.
Summary:
A sensor (transmitter) measures: and this measured signal is then used to monitor the differential pressure, or to use as a measurement signal for an external controller.
A controller (PI controller) controls: somewhere within the range of the sensor you program a set point. And the differential pressure controller will control the fan or valve via its output in such a way that the value it measures corresponds to the desired set point.
Autotune
This differential pressure controller works with a so-called PI control. And such a PI control is quite complicated to set. But fortunately, the Sentera differential pressure controllers are equipped with an autotune function. You only have to determine the desired set point and the controller does the rest. We will go into this in more detail below, but you can safely skip this part.air speed control in ventilation systemHow does a PI control work?
A PI control can best be viewed as a kind of "loop". The differential pressure regulator (just like a transmitter) continuously performs measurements. The difference with a transmitter, however, is that its output does not increase proportionally as the differential pressure increases. But, it continuously adjusts its output (and therefore also the fan or valve), in order to obtain the desired set point as a measured value.
Initially - immediately after starting from a standstill - the measured value will be far removed from the desired value (the set point). The controller will then react violently (resulting in major changes in the speed of the fan). As a result, it goes very quickly to the set point. Probably even beyond it, causing it to quickly reduce the speed again. But slightly less violently than the first movement. Eventually, these fluctuations will decrease in proportion and "land" on a nice stable signal that corresponds to the set value. You now have a stable fixed differential pressure.
As pressure drops or builds up, the output of the controller is automatically corrected. In order to maintain the set point.
Incidentally, a delay is also built into a PI control. In such a way that at the slightest pressure difference (e.g. someone opening a door), the fan does not start to compensate excessively. The delay gives it time to correct calmly. Because, there is nothing as annoying as a pressure control that is set "too" reactively. But thanks to the AutoTune function, you will not have this problem.Practical applications : VAV control
One of the practical applications of a differential pressure regulator is a VAV (Variable Air Volume) control system:
Imagine a network of ventilation ducts where one large roof fan is used to extract polluted air from different rooms, each equipped with an adjustable air grille (control damper).
Each room opens its exhaust damper (automatically controlled or not) depending on the need for fresh air.
In such a situation, a PI differential pressure regulator in the main duct (where all the other ducts come together) will automatically adjust the speed of the roof fan in order to keep the pressure in the duct constant, regardless of how many rooms require air.
The result is that each room is effectively extracted depending on the position of the damper. And that this is not affected by the position of the dampers in the other rooms.
Differential pressure, air volume flow or air velocity?
Technically, this differential pressure regulator only regulates the differential pressure [Pa]. But based on this measurement in Pascal, the device itself can calculate the air flow [m³/h] or the air speed [m/s].
To regulate on air flow [m³/h] there are 2 possibilities:
Either you have the K-factor of your fan. In that case, it is sufficient to enter that value in the Modbus register provided for that purpose. Furthermore, you simply perform a pressure measurement. So with the help of the connection sets PSET-PVC-200 or PSET-QF-200. The air flow is calculated automatically and you can read it via the Modbus registers.
If you do not have the K-factor of your fan, or the setup does not allow you to use it reliably, there is also the possibility to perform a measurement of the air speed [m/s]. This is usually easier to perform. For this you will need the optional PITOT tube connection set: PSET-PTS-200 or PSET-PTL-200. Because you want to control on air velocity [m/s], it is necessary to enter the duct cross-section [cm²] in Modbus, after which you can read out the air flow [m³/h] again via Modbus.
The setpoint can therefore be entered in Pascal, m³/h and m/s.

Visual indication
This differential pressure controller provides a clear visual indication of the differential pressure, air velocity or air flow level via the green, yellow and red LEDs. The green LED indicates that the measured value is within the set range. When the measured value is within the warning range, the yellow LED lights up. And red means that the value is completely out of range. The second green LED indicates the sensor status. It is activated when the power and Modbus RTU communication are switched on.

Analogue output for controlling an EC motor, frequency controller or valve actuator
This controller transmits the EC fan speed (or the control signal for the AC fan speed controller) via its analogue output. This can be a 0-10 VDC control signal, but you can also change this to 0-20 mA or 0 to 100% PWM via Modbus.

Setting via Modbus
All parameters can be set via Modbus RTU

Reduced installation time
The power supply, analog output and Modbus RTU communication are connected via the terminal block with spring clamps. This eliminates the need for routine checks and guarantees reliable contact. For both stranded and hard core wires.

Power over Modbus
Sentera developed the Power over Modbus (PoM) concept to reduce costs, increase reliability, and simplify cabling in Modbus networks. So, for example, as soon as multiple sensors are in the same network, they can use the same power supplies, converters, gateways, etc. For this purpose, most Sentera products are available in a PoM version that is equipped with one or more RJ45 connections. Be sure to also check out the Sentera power supplies.

High-quality housing
The housing is made of high-quality r-ABS VO (UL94) plastic. This material is heat-resistant and offers good protection against impacts. The connections for the pressure lines are made of aluminum. The housing offers IP65 protection against the ingress of dirt and water. This sensor can be mounted on the wall.