Standard Pneumatic Products, Inc

Installation: (Scroll down for PDF downloadable wiring diagrams)



The UNIVERSAL AutoDual is a modern energy savings controller that will operate your air compressor at its maximum level of efficiency and with the optional Emergency Shutdown feature, will protect your compressor from failure from oil loss or high discharge air temperature. The Autoatic Tank Drain option will automatcaly drain the condensate from your receiver tank with virtually no wasted air, or the tank may be drained manually with the convenient manual tank dran button mounted on the AutoDual.

The UNIVERSAL AUTODUAL was designed to be simple to install and requires only two plumbing (air) connections and two electrical connections to use all of the standard features.

Preparing the Air Compressor

  1. Remove the existing pressure switch, pilot unloading valve, and special valves associated with these controls from the air compressor.
  2. Mount the UNIVERSAL AUTODUAL to the compressor platform using the flanges on the rear mounting plate of the enclosure or as a remote mount to an adjacent wall.
  3. Plumb compressed air from the air receiver into the bottom ¼" connection of the UNIVERSAL AUTODUAL and then connect the compressor head unloader control air line directly to the ¼" outlet connection on the lower left side of the AutoDual.
  4. Select the power switch to the "Off" position.
Plumbing is now complete.


The lead wire supplied on the upper right side of the AutoDual (labeled "Power Out Starter Coil") is wired to the starter coil exactly like the lead on a standard pressure switch except that the AutoDual requires attention to the voltage. Your selection of the Universal AutoDual AD-115 (115 volt) or AD230 (230 volt) MUST match the coil voltage on the starter. Remember, the coil voltage requirement to engage the starter contacts and the actual motor voltage requirement may be 2 different values. (Example: 460v 3phase motor voltage, 115 volt starter coil) You CANNOT attach any 460-volt power directly to the AutoDual without damaging it.

For a 3/60/460 or 3/60/575 volt main power system, The starter requires two items to operate the UNIVERSAL AUTODUAL successfully (see wiring diagram):

Item I. A step-down transformer (CVT) to convert the 460 or 575 volts to supply input power the AutoDual (lower right hand lead) to 230 or 115 volts. For 115 volts, you have the option of powering the AutoDual from a 115-volt wall socket, or wiring the CVT (Control Voltage Transformer) to deliver 115 volts.

Item II. In all cases the starter COIL VOLTAGE must match the Universal AutoDual input voltage, either 230 or 115 volts, single phase.

The simplest way to wire the AutoDual is 1/60/115 volts. This requires that you plug in the AutoDual power-in lead to a 115 volt socket, and then wire the control power to the starter coil (see diagram). However, the starter coil MUST BE 115 volts regardless of the main inlet motor voltage.

For 230-volt main power inlet or for power transformed from 460 to 230 volts, the AutoDual is available as a 230-volt system (Model AD230). In this case you would power the AutoDual directly from the 230-volt hot side of the starter (single phase L1 and L2 (neutral)) or after the CVT (460 to 230v) voltage step-down, and then run the control power to the starter coil. The coil voltage must be 230 volts. If 115-volt control voltage is a requirement, then use a UNIVERSAL AUTODUAL (Model AD115) for 115 volts. Use a CVT (Control Voltage Transformer) to convert down from the 3/60/575,460 or 230 volt main power to 1/115 volt or plug in the UNIVERSAL AUTODUAL power-in to a standard 115-volt socket. Connect the control power lead to the 115-volt starter coil (see diagram) and the wiring is complete.

In all circumstances when wiring to the starter coil, it is a requirement to wire one leg through the dry contact auxiliary switch (normally on) located on the thermal overloads section of the starter (see diagram) to obtain a "stop" on the coil voltage if the starter overload relay trips.

When the wiring job is completed and is checked for correctness select the mode of operation start/stop or AutoDual (select unloaded time) and push the "ON" rocker switch. This will power the air compressor and it will start.

Please do not hesitate to call us at Standard Pneumatic Products, Inc. for assistance when wiring in a UNIVERSAL AUTODUAL. The price of a phone call is way less costly than a mis-wired UNIVERSAL AUTODUAL.

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Wiring Diagrams:

All wiring diagrams and configuration Drawings may be viewed with the FREE Adobe Acrobat reader.
If you need the reader, download it here. 

115 Volt Without Control Voltage transformer  115VAC, single phase, to a 115 volt Starter Coil, with a 115/230V, 115/230 Single phase contactor.

115 Volt with C.V.T115VAC, single phase, to a 115 volt Starter Coil, Using a control voltage transformer on 230, 460, 3 phase Contactor.

230 Volt without Control Voltage Transformer  230VAC, single phase, to a 230 volt Starter Coil, with a 230V 1 or 3 phase contactor.

230 Volt with C.V.T.   230VAC, single phase, to a 230 volt Starter Coil, Using a control voltage transformer on a 460, 1 or 3 phase contactor.

Configuration Drawings:  The unique versatility of the Universal AutoDual is demonstrated in the following configuration drawings. Due to the many differrent compressor combinations available, your specific requirement may not be shown. Contact Standard Pneumatic Products to discuss any application you are interested in that is not shown here.

Single Compressor Configurations:

Standard Configuration - Standard Universal AutoDual configuration. This drawing covers most AutoDual head unloader installations with existing motor starter.

Standard Configuration - Model ADS - Universal AutoDual/Starter Combination. This drawing covers most ADS Head unloader installations w/o motor starter.

Compressor w/o Head Unoaders - This drawing covers compressor installations WITHOUT head unloaders. It utilizes a Kingston 621 atmospheric discharge valve, controlled by the Universal AutoDual Model AD shown. Also works with ADS Starter Combination.

Oil Free Double Acting - Standard Configuration for Oil-free Double Acting Compressor

Pilot Control Valve - Quincy O.E.M application with Quincy unloader valve Modification.

Lead/Lag Configurations:

Standard Lead-Lag Configuration - Utilizes 2 Universal AutoDual Controllers, the Standard AD, or Model ADS with starter (shown), with manual Lead-Lag switching between a reciprocating compressor and a rotary screw compressor.

Double Acting - Shown in lead/lag configuration with a Rotary Screw Compressor. Utilizes 2 Universal AutoDual Controllers, (Standard AD shown, or Model ADS with starter) with manual Lead-Lag switching.

Rotary Screw - Shown in Lag only configuration on "standby" Rotary Screw Compressor.

Air Cooled Rotary Screw - Shown in Lag only configuration with "standby" recip compressor.

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