XD4

A closed control circuit for regulation of the volume flow rate, i.e. measuring - comparing - adjusting, is characteristic of air terminal units.
The volume flow rate is determined by measuring a differential pressure (effective pressure). This is done via a differential pressure sensor. An integrated differential pressure transducer converts the effective pressure into a voltage signal. The volume flow rate actual value is hence available as a voltage signal. Due to factory adjustment, 10 V DC always corresponds to the nominal volume flow (q_vnom).
The volume flow rate setpoint value is specified by a higher-level controller (e.g. room temperature controller, air quality controller, central BMS). Variable volume flow control results in a value between q_vmin and q_vmax. It is possible to override the room temperature control, e.g. by a complete shut-off of the duct.
The controller compares the volume flow rate setpoint value to the actual value and controls the external actuator accordingly. If the supply voltage is interrupted or the wire breaks, the spring return actuator moves to the fail-safe position OPEN (NO) or CLOSED (NC) as specified in the order code.

Universal controller for VAV terminal units

① TVR, TZ-Silenzio, TA-Silenzio, TVZ, TVA, TVRK up to NW 250

② TVJ, TVT up to dimensions 1000 x 500, TVRK from NW 315

Universal controller XD4, type GUAC-SM3 for VAV terminal units

* When dimensioning the transformers and the supply cable for the universal controller, the power consumption of the associated actuator must be taken into account.
** Input can be connected to supply voltage as part of override control.

Actuator with spring return 341C-024-05-V/ST06

Actuator with spring return 361C-024-20V/ST06

Display range of functions

Display functions

• Volume flow rate actual value (unit optionally m³/h, l/s)
• Display via 3-character display with position valuation labelling (upstroke symbolises thousands of digits)
• Status and error display for various operating modes, including display of activated override control, display of diagnostic function
• Display of the firmware version

Setting options

• Unit of the volume flow rate display m³/h or l/s
• Work areas q_vmin, q_vmax
• Signal voltage range 0 - 10 V or 2 - 10 V DC

Diagnostic function

• Activation of override controls OPEN, CLOSED, q_vmin, q_vmax, motor stop

Commissioning

• On-site adjusting is not required
• Due to the volume flow rates set in the factory, always ensure that the control units are only installed in the specified locations
• After successful installation and wiring the controller is ready for use
• Comply with the volume flow control range of the volume flow controller, in particular do not fall below the technically minimum volume flow rate
• Only briefly remove the protective cap of the control component during wiring

Product details

Analogue interface 0 – 10 V or 2 – 10 V DC (operating mode V, F)

The analogue interface can be adjusted for the signal voltage range 0 – 10 V DC or 2 – 10 V DC. The assignment of the volume flowrate setpoint value or actual value for voltage signals is shown in the characteristic curves.

• The set signal voltage range is always equally valid for setpoint value and actual value signals.
• The signal voltage range is pre-set in the factory in accordance with the order code entries.
• Signal voltage range can be adjusted on site in the adjustment menu on the display, via adjustment device or PC software.

• In the operating mode V (variable operation), the setpoint value is specified with an analogue signal on terminal Y.
• The selected signal voltage range 0 – 10V or 2 – 10V DC is assigned to the volume flow rate range qvmin – qvmax a change packet.
• Volume flow rate range qvmin – qvmax pre-set in the factory according to the order code entries.
• Subsequent adjustment of qvmin or qvmax on the display, via adjustment device or PC software.

• In the operating mode F (constant value mode), an analogue signal is not required on terminal Y.
• It is controlled by the volume flow rate constant value set by qvmin set volume flow rate constant value regulated.
• Volume flow rate qvmin is pre-set in the factory according to the order code entry.
• Subsequent adjustment of qvmin on the display, via adjustment device or PC software.

Actual value as feedback for monitoring or tracking control

• On terminal U, the actual volume flow rate measured by the controller can be tapped as a voltage signal.
• The selected signal voltage range 0 – 10 V DC or 2 – 10 V DC is shown in the volume flow rate range 0 – qvnom shown.

Override control

For special operating situations, the volume flow controller can be put in a special operating mode (override control). The followingare possible: control qvmin, control qvmax, damper blade in the OPEN position or damper blade CLOSED.

Override control via signal input Y

With appropriate wiring on the signal input Y, the override controls can be activated according to the connection diagrams via wiringwith external switch contacts/relays. OPEN and CLOSED are only available if the controller is supplied with alternating current (AC).

Override control CLOSED via control signal Y

• With signal voltage range 0 – 10V DC: CLOSED is activated when qvmin = 0 is set and the control signal is Y < 0.5V DC.
•  With signal voltage range 2 – 10 V DC: CLOSED is activated when control signal is Y < 0.8 V DC. 0.8 V = factory setting 
• The specified switching point of 0.8 V corresponds here to the factory default setting.

Override control for diagnostic purposes 

• For test purposes, the override control can also be activated via the built-in display, a adjustment device or the PC software.