The SmartServer IoT requires a 10.5 – 30VDC or a 12 – 30VAC 50/60Hz power source attached to the power input on the SmartServer.  The power source must provide sufficient power for both the SmartServer and any attached USB devices.  This section describes how you can determine the external low voltage power requirements and describes how you can connect the power source to the SmartServer power input. It consists of the following:

DC Power Source Requirements

You can use a DC power source with the SmartServer.  The following table summarizes the SmartServer DC power requirements as well as the power requirements from typical devices that you will plug into the SmartServer.  Select a power source that can supply the required power across the temperature range where you intend to use it.

Example scenario: To power a SmartServer IoT Pro EX with four U60 FT channels, the selected power source must supply at least: 13 + (4 * 1) = 17 W.

AC Power Source Requirements

You can use a AC power source with the SmartServer.  The following table summarizes the SmartServer AC power requirements as well as the power requirements from typical devices that you will plug into the SmartServer.  Select a power source that can supply the required power across the temperature range where you intend to use it.

If you are using an AC power source, the power source output must not be grounded to earth/safety ground. 

In the U.S., the NEC requires that one leg of the secondary of a 24 VAC Class 2 transformer must be connected to earth when the voltage of the primary side exceeds 150VAC. Some code jurisdictions require this ground connection in all installations. Code also requires protection fuses on the secondary, and in some cases, on the primary as well.  If any of the outputs of our AC power source are grounded you must provide a 1-1 isolation transformer that does not connect the secondary to earth/safety ground as shown in figure below.

AC power SmartServer IoT with a 240 VAC power source. NEC code mandates connection to earth on the secondary of the first transformer with an isolation transformer to  power the SmartServer IoT.

Avoid this connection scheme if you have a grounded input.

Sharing the SmartServer Power Source

The SmartServer uses a full-wave bridge rectifier as the input to its internal power supply.  As a result, you cannot connect the power source that you use with the SmartServer to other low voltage components that use a half-wave bridge rectifier as the input to their internal power supplies.  You also cannot connect the power source that you use with the SmartServer to other low voltage components that connect either power input to earth or safety ground.  If you connect the power source that you use with the SmartServer to a device with a half-wave bridge rectifier or with a power input connected to earth or safety ground, the SmartServer will not operate and may become inoperable.

It is common to supply power to multiple low voltage control components in a control cabinet, where one of the low voltage components is the SmartServer. Doing so requires consideration of the power supply design for each device that is connected to the secondary of the transformer.

Using the U70 PL-20 as a Power Source

You can use the U70 PL-20 as a power source for the SmartServer.  See Using the U70 as a SmartServer Power Supply and Power Line Network Interface for more information.

Connecting the Power Source

Connect the power source to the right two connectors on the power input shown in the following figure. The power input is polarity insensitive so you can connect the two power inputs to either power input pin. You can optionally connect the ground input to earth ground. A ground connection is not required unless you require an earth ground connection for either of the RS-485 interfaces as described in Using the SmartServer Connectors.

The screw terminals accept 0.22mm² – 3.3mm² (22 – 12AWG) gauge solid wire. The optimum tightening torque for the screw terminals is 0.5 Nm (4.4 lbs. in.) maximum. The ideal flathead screwdriver tip width for use with the screw terminal connectors is 3mm (0.12”). Strip wires to a length of 7mm (0.28”). You can use an insulated cord pin end to prevent fraying and inadvertent contact with adjacent terminals.  

When you apply power to the SmartServer IoT, the LEDs on the SmartServer IoT will flash as the unit boots. Once the unit is powered and operational, the blue Power/Wink LED will stay on solid.