What is a ground relay?

The SWARTZ Type64 Ground Relay serves dual functions when used with high-resistance grounded DC switchgear. The Type64 relay was designed to alert personnel to “ground” or “hot” faults in DC switchgear, rectifiers, and enclosures. These high-resistance relays offer superior performance and reliability due to their solid-state components. They are also ruggedly constructed and feature self-diagnosing capabilities.

The following are examples of:

  • Construction by draw-out
  • LED Meter – Accurate and easy to read
  • Transient Surge Protection

“Hot structure” faults can be detected in both AC and DC systems. The internal power supply automatically compensates and operates with a wide variety of DC inputs. Internal time delays are in place to prevent nuisance trips.


Swartz Type 64r Ground Relays with High-Resistance Structure alert personnel through visual and audio output contacts when DC switchgear or rectifiers become grounded due to a breach in insulation. The relay will announce when it detects a fault or when its self-diagnosis feature indicates that an internal component has failed. It will also alert personnel if there is a fault or leak between the bus and the structure (hot structure). Normally, the relay’s output is connected to the lockout relay to de-energize all the stations. The hot structure function can detect both AC and DC faults and leakages. The setpoints of the ground structure announcement and hot structure trip can be adjusted. On the front panel, there are test buttons for both hot structure trips and ground structure trips. The Structure Ground Relay provides continuous operation in the event of faults, and lockout conditions do not occur if the voltage does not exceed 600 VAC or 700 VDC, with 600 VDC superimposed (rectifier failures).

For nearly half a century, Swartz Engineering has been at the forefront of industry safety. They are a family-owned company specializing in power distribution for the electrical industry. They are the leading manufacturer of 64r relay. It is the most widely accepted protective overcurrent device used in the transit industry today.