Controlled Isolation in Relay Testing

In some overseas project specifications, directly powering the protection device from the cabinet DC supply during testing is not allowed. Test power must be electrically isolated from the live system.

The power-module version of the ODES TSB-14 testblock provides a compliant, safe solution. With the correct handle and wiring, it supplies stable DC power to the relay throughout testing—no cabinet rewiring, no safety compromise, and full electrical isolation.

Selection Made Simple — Know the Slot and the Handle

• Slot rule: In every TSB-14 testblock, the power module (O) is fixed at position 7. Example: TSB-14-222211O1ABAAAB

• Handle match: Always use the FT-14-R standard test handle.

Once you know these two facts—slot 7 and the matching handle—your selection will always line up correctly.

Tip: Inside the TSB-14, modules follow a fixed logic: Current → Voltage → Power → Trip → Signal. Remember “power comes after voltage” and you’ll always spot the O-module at a glance.

Two Operating States — “Normal” and “Test”

Each power-module testblock includes a shorting bar under a protective cover, which defines the circuit state:

• Normal (non-test) mode: Cover closed → bar in place → normally open contact closed → circuit energized.

• Test mode: Cover removed → bar withdrawn → contact open → waiting for the test handle to take control.

This simple “cover on = energized / cover off = isolated” rule ensures that power can only be transferred to the test side intentionally—never by accident.

Entering Test Mode — Why Short Terminal 13 and 14

When testing begins, insert the FT-14-R handle. Before insertion, short terminals 13 and 14 on the handle using a DCC-4 mm test lead.

Purpose:

• Keeps the power circuit continuously closed throughout testing.

• Prevents the protection relay from losing power and issuing false alarms or trips.

In summary: shorted Terminal13-14 = guaranteed stable power supply. You can plug and unplug other circuits without the relay ever losing DC.

Common Mistakes to Avoid

• Forgetting Terminal 13-14 are shorted: The relay may momentarily de-energize and alarm. Always short before inserting the handle.

• Ignoring the cover logic: “Cover off = open circuit.” Don’t assume power stays on without the handle inserted.

Choosing an ODES TSB-14 with a power module is the simplest way to achieve both reliable supply and electrical isolation during relay testing:

• Clear position: slot 7 = O-module

• Simple operation: cover on = on, cover off = off

• Standard handle: FT-14-R

• Controlled risk: short 13/14 to ensure uninterrupted power

This configuration saves rework, prevents mis-operation, and meets international safety standards for energized testing.

Need a safer way to power protection relays during testing?

• Ask for the TSB-14 configuration guide showing power-module layouts and handle wiring.

• Talk with our engineers about compliance requirements for isolated test power.

• Keep your testing workflow efficient, consistent, and fully IEC-compliant.

Contact:📩 tonyzhang@odes.com.cn

Or visit:🌐 https://www.odes-electric.com/

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