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Electric acuator AT 3940 (15-70 Nm)

Electric actuator for on/off or control of ball valves, butterfly or where a 90° rotation is required.

Torque15 Nm to 70 Nm
DrivenElectric 85-260 V 50-60Hz and 24VDC
Fits valves:AT3502, AT3507, AT3533S, AT3534S, AT3542, AT3547, AT3582, AT3585, AT3590, AT2282, AT 2310-2319, AT2270B


Article number Performance Control signal/Communication Torque (Nm) Power supply Operating time (s) Amount
AT 3940-1 Electric On/Off On/Off 15 230V, 24VDC 13
AT 3940-1-POS Electric positioning 4-20mA 15 230V, 24VDC 13
AT 3940-3 Electric On/Off On/Off 30 230V, 24VDC 15
AT 3940-3-POS Electric positioning 4-20mA 30 230V, 24VDC 15
AT 3940-7 Electric On/Off On/Off 70 230V, 24VDC 15
AT 3940-7-POS Electric positioning 4-20mA 70 230V, 24VDC 15

Product information

Range of application

Weather-proof actuator for on-off actuation or control of ball valves, butterfly or where a 90° rotation is required. Torque 15, 30 or 70 Nm.


UEC.11 Valve actuator, electric, two-position without spring return
Actuator Bernard Electrical AT 3940 for 90°. Maneuvering of ball-, butterfly- or where a 90° rotation is required.

Quality assurance


EC Directives 2004/108/EC, 2006/95/EC and fulfills the EN 61000-6-4, EN 61000-6-2, EN 60034-1 and EN 60529.

IP 68 rated.

Material specification

DetailMaterialSurface treatment
2CopeAluminumEpoxy-painted RAL 1014, C3 acc. to ISO 12944
3Drive shaftSolid steelUntreated

Dimension and weight

Actuator/Fig. noStandard drive shaftABC


3940-114x14, 11x11, 9x91501451752,5
3940-314x14, 11x11, 9x91501451752,5
3940-722x22, 17x17, 14x14, 11x111501451753,5
Dimension in mm, weight in kg.

Function and design

Standard version
Reversible actuator in four sizes, for 0-90° rotation, adjustable through a combination of cams, mechanical end stop and/or torque switch.

The acutator is a compact combination of an electric motor with a thermal overload protection and self-locking, permanently lubricated worm gear. Standard with manual emergency operation and position indicator.

The actuator mounting-dimensions in relation to the fittings are according to ISO 5211.

Design lifetime 20 000 cycles for on/off or 300 000 starts for modulating (positioning). Tested according to EN 15714-2 class A and B

Standard performance

Standard performance
Motor dutyS4-30% ED. 120 starter/h max
Temperature-20°C to +60°C
Anti condensation heaterYes
Overload protectionThermostats

Permanently lubricated gear

Cable entries2 st.M20x1,5
End position switches250VAC-5A, / 48VDC-2, 5A

Technical data

Actuator 3940

Torque NmOperating time (s)ISO-ConnectionDrive shaft230 VAC 50 Hz24VDC


Square in mmStopKwStart (A)Stop (A)kWStart (A)Stop (A)kW
1154513F03/04/0514, 11, 90,40,020,80,30,022,50,40,02
3306015F03/04/0514, 11, 90,60,030,80,30,022,50,40,02
77010015F05/0722, 17, 14, 111,20,0610,40,02603,50,02


Valve typeDp, bar
Ball valve 3-piece25DN10-2532-4050
Ball valve25DN15-2532-4050-80
Ball valve flanged16DN15-2025-4050-65
Butterfly valve16DN50-150

Accessories and options

AT3940 is available in three different variants

1. On/off with electromechanical circuit breaker.
2. On/off with a feedback signal 4-20 mA.
3. Regulating with control signal 4-20 mA in and out.


During all work with the actuator the power MUST be disconnected.
- The actuator must be connected as per the wiring diagram, see the manual.
- Each actuator must be powered by an individual switch or relay contact, minimum 16A, to prevent cross-feed between the actuators.
- Installation with the motor downwards should be avoided.
- Turn the valve with the control unit's hand wheel to centre position. See indication on top of the device.
- Always connect the heater.
- Check that the actuator turns the valve in the desired direction.
- The correct limit switch (open or closed) shall then break the motor current.
- Cable entries must comply at least to the lowest protection class of devices.

See the manual for start-up , storage and maintenance.


Article number, manufacturer, serial number, voltage and current.
Wiring diagram is placed by the motor at delivery.

How to order

Example: 3900-4-3A3A
AT3940-1, 3, 7*3**A***-POS or PT**A*****
Fig. no.SizeOperating timeConnectionOptionsOptions
Example: 3940-7-POS (Regulating, 70 Nm, with control signal 4-20mA)
* 1, 3 or 7 depending on the required torque 15, 30 or 70 Nm
* * Options (POS = Positions 4-20mA, PT = Feedback signal 4-20mA)