Schneider TeSys GV5/GV6 Motor Circuit Breaker Operation and Protection Guide

3.3 Extend the door lock function of the handle

The extension handle comes standard with locking the door in the I (ON) position. It can also be temporarily disabled, but reference should be made to GHD16292AA (GV5) or GHD16320AA (GV6). Typical application scenario: When the handle of the circuit breaker in the incoming cabinet is in the ON position, the door is locked to ensure that other motor circuits are still live when the door is opened for maintenance, but the operator cannot touch the busbar.

3.4 Isolation Capability

The TeSys GV5/GV6 equipment complies with the isolation requirements of IEC/EN 60947-1 and 60947-2, and the isolation symbol is marked on the nameplate. Place the handle in O (OFF) and lock it to safely carry out downstream equipment maintenance work.

Detailed explanation of protection function

This series of trip units integrates multiple protections and can be set through panel dialing. The following table shows a list of key parameters:

Parameter function adjustment range default value SDTAM linkage

Ir overload protection setting current 0.4 × In~In 0.4 × In is

Class Tripping Level 5, 10, 20 10 No

Isd short delay protection setting multiple 5-13 × Ir 13 × Ir No

Tsd short delay fixed delay not adjustable (20ms hold+60ms maximum break) - No

Ii instantaneous protection multiple fixed at 15 × In - No

Lunbal phase loss/imbalance protection fixed at 30% - Yes

Tunbal Unbalanced Delay Start at 0.7s/Steady State 4s - No

4.1 Overload/Thermal Protection (ANSI 49)

Adopting I ² t inverse time characteristic and simulating motor thermal imaging (including iron loss and copper loss). The Ir setting value is set through multi gear dialing (e.g. 150A trip unit: Ir gear ranges from 70A to 150A). The maximum tripping time for Class corresponding to 7.2 × Ir is:

Class 5: 4-5 seconds

Class 10:8-10 seconds

Class 20:16-20 seconds

Thermal memory function: The release unit will remember the heat accumulation in the past 20 minutes. Even if there are multiple short-term overloads (a single one is not enough to trip), the accumulated heat will still cause the final trip, which more accurately reflects the temperature rise of the motor.

Self cooling motor: Thermal imaging calculation assumes that the motor is self ventilated (shaft end fan). If the motor is for forced ventilation, it is necessary to reduce the rated use or consult the manufacturer.

4.2 Short Delay Protection (ANSI 51)

Short delay protection is used to avoid motor starting current (usually 6-8 × Ir) and quickly cut off short circuits at the end of the feeder. Isd can be set to 5-13 × Ir (step size 1 × Ir). The fixed time delay is:

Holding time: 20ms (allowing starting current to pass)

Maximum breaking time: 60ms

This protection is combined with instantaneous protection to achieve selective coordination.

4.3 Instantaneous protection (ANSI 50)

The instantaneous protection is a fixed value of 15 × In (In is the maximum rated current of the trip unit). For example, the GV6 device with 320A has an instantaneous operating current of 4800A, an accuracy of ± 15%, and a maximum breaking time of 30ms. This value is much lower than the contact repulsion level, ensuring rapid breaking under extremely high short-circuit currents.

4.4 Phase Loss/Unbalance Protection (ANSI 46)

Unbalance calculation formula:

Iavg=I one+I two+I three three,unbalance ratio=max(∣Ik−Iavg∣Iavg)×one hundred%

I avg= threeI one+I two+I three

Imbalance rate=max（I avg∣I k−I avg∣)×100%

Fixed setting value of 30%. The delay is divided into two sections:

Start up phase: 0.7 seconds (greater risk of imbalance during motor start-up)

Steady state phase: 4 seconds

Phase loss (zero current in one phase) belongs to extreme imbalance and also triggers protection. This protection cannot be turned off and is always in effect.

Reflex Tripping

The unique reflective trip system of TeSys GV5/GV6 uses the pressure generated by short-circuit current to directly drive the piston to impact the trip mechanism, without the need for an electronic trip unit. This makes the breaking speed extremely fast (less than 10ms), especially suitable for situations with high expected short-circuit currents. The reflection trip curve is only related to the rated current of the equipment and does not depend on the setting.

Practical significance: In cascade protection, the reflection trip of upstream GV5/GV6 can limit the short-circuit current of downstream equipment, allowing the use of lower level switches with lower breaking capacity, thereby reducing costs.

Electrical auxiliary accessories and fault indication

6.1 Indicator contacts (OF, SD, SDE)

OF: Indicates the position of the main contact (ON/OFF)

SD: Indicates any cause of tripping (including manual push testing, undervoltage tripping, overload, short circuit, phase loss)

SDE: Only indicates electrical fault tripping (overload, short circuit, phase loss), excluding manual testing and voltage trip operation.

The logical states of these contacts are detailed in the table below (using NC/NO transformation):

Handle position OF (1 → 2) SD (1 → 2) SDE (1 → 2)

OFF Close Close Open