This month’s Techtime covers the information required to be able to wire various equipment to our controllers. Before proceeding, remember that Neptronic controllers are configurable, which means two things:

1. Even though the device is connected to the right type of input or output, this does not mean that it is the correct configuration.
2. If the configuration you are looking for does not exist, it will most likely not work properly.

For example:

• Equipment: Duct Heater
• Type: Output
• Function: Heating Ramp
• Control Signal: 0-10Vdc

Note that valves can be direct or reverse acting. This information is very important since not all controllers have the ability to reverse the signal. This issue could be solved by using an external relay if the controller is already installed.

he same applies to sensors, transducers, and relays:

• Equipment: STC8-11 temperature sensor
• Type: Input
• Function: Changeover
• Control Signal: 10kΩ type 3

Once the equipment list is completed, you must refer to the Specification & Installation instructions to identify the possible terminals to be used. This document details the default configurations of the controller and the specific order in which they should be programmed. Sometimes, we can find a preconfigured input or output that matches the equipment requirements. This step allows us to reduce configuration time for the client. If there are no defaults available, then identify which terminal you will be using for the device.

Note concerning the Commons

All of the equipment that needs to be wired requires at least two wires; common & signal. The common is the base or reference for the control signal. When you have multiple devices on the same controller, it is important that the common is the same for all. This is why we often recommend grounding the neutral leg of the transformer. This is especially true when multiple transformers are used on the same controller or multiple controllers connected together for a specific function, such as night setback.

When the transformer's neutral is not grounded (also referred to as a "floating transformer"), it is possible for the common to have residual charge. This residual charge will influence the signal sent to the devices from the controller. The voltage sent from the controller will not be the same as the voltage measured at the device terminal strip.

The configuration structure is a little different from the TUCB and EFCB series. It is the only controller with 2-pipe or 4-pipe configuration which is equivalent to changeover ramp in other controllers. It is also the only controller that uses Reheat which is equivalent to Heating Ramp 2. Note that all the commons on the Neptronic controllers are all internally linked together. Applying a voltage on one common will affect the entire controller’s behavior.

Signal

Analog signals are influenced by external power sources such as light ballasts and variable frequency drives (VFD). Staying away from these electrical fields is important. If you believe there might be some electrical interference, a shielded wire can be used. Digital (Binary) signals are also affected, but not enough to make any significant difference.

Types of Inputs & Outputs

Other Device Power Supply

Some equipment may require an additional wire to power up the device. Depending on the model, the 24Vac power supply can be from the controller board or connected to the transformer directly.

Wire Gauge

The wire gauge for controls is found on the specification sheet of the controller.