Product Line:
Surge Protective Devices (SPD's)

Dry Contact Functionality in SPD Devices

Dry contacts are included in Schneider Electric surge protection devices such as HWA, HWC, HWG, EBA, EMA, EMB, EMD XDSE, Surgeloc, I-Line, and IMA to provide optional remote status indication. These contacts are typically used to interface with a Building Management System (BMS), computer interface board, or alarm panel, allowing remote monitoring of the SPD’s operational status.

Trigger Mechanism

The dry contact is controlled by the SPD’s internal status monitoring circuit. It changes state based on the health and power status of the SPD:

• Alarm Condition (Fault or No Power):

  • The contact is closed between NC (Normally Closed) and COM (Common).
  • This indicates either a loss of power to the SPD or a failure of the suppression components (e.g., thermal disconnect activation or module degradation).

• Normal Operating Condition (Power Applied, No Fault):

  • The contact is closed between NO (Normally Open) and COM.
  • This indicates the SPD is powered and functioning properly.

This change in contact state allows external systems to detect when the SPD has entered a fault condition or lost power.

Contact Type and Ratings

• Form C (SPDT) configuration:
  • Terminals: NO (Normally Open), NC (Normally Closed), COM (Common)
• Electrical Ratings:
  • Maximum Voltage: 24 V AC / 24 V DC
  • Maximum Current: 2 A

These ratings are suitable for low-voltage signaling applications. For higher voltage or current requirements, an external relay should be used to isolate and scale the signal appropriately.

Optional Wiring

Wiring the dry contact is not required for SPD operation. It is provided as an optional feature for users who want remote fault indication or integration with supervisory systems.

Dry Contact State Summary

Released for: Schneider Electric Canada