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Budget Contract Files Change Order Contract Amount table Preview Preview Ground Fault Protection: Zero Sequence: Summation Method: Zero Sequence Circuit feeders are fed through a current transformer. A zero sequence relay or circuit breaker trip unit ensures that the circuit current feeding the load will return to the source returns on those same conductors . If the current is returning to the source through a different path (usually ground), the ground-fault relay will detect this difference. If the diffrence in current exceeds a pre-determined amount for a pre-determined amount of time, the ground-fault relay will operate. Under normal operating condictions, the vector sum of the circuit currents should equal zero Phase Currents + Neutral Currents = 0 \[I_{a}+I_{b}+I_{c}-I_{n}=0\] Summation Method Direct measurement of all phase and neutral current through a protection device's current transformers is evaluated. All phase currents feeding a load should return to the source. A ground fault some where downstream will create a difference in the returning current. Phase Currents = Return Currents \[I_{a}+I_{b}+I_{c}=I_{n}\] Primary Current Test Stationary and moving contacts are built from alloys that are formulated to endure the stresses of electrical arcing. However, if contacts are not maintained on a regular basis, their electrical resistance due to repeated arcing builds up, resulting in a signifi cant decrease in the contact’s ability to carry current. Excessive corrosion of contacts is detrimental to the breaker performance. One way to check contacts is to apply DC and measure the contact resistance or voltage drop across the closed contacts. The breaker contact resistance should be measured from bushing terminal to bushing terminal with the breaker in closed position. Secondary Injectoon Testing Solid-state trip units can be tested via secondary current injection using a test set specifically designed for the device to be tested. The main shortcoming of the secondary current injection test method is that only the solid-state trip unit logic and components are tested. Unlike primary injection, this test method does not verify the current sensors, wiring, or circuit breaker current carrying components. This is the main reason why the primary injection test method has superiority over secondary injection testing. No-Trip: The protective functions of the electronic trip device can be tested, but the trip device won't send a trip signal to the circuit breakers trip actuator. This test can be performed while the circuit breaker is energized and carrying load current because a no-trip test won't cause the circuit breaker to open. Trip Mode: The protective functions of the electronic circuit are tested just like a no-trip mode test, except the trip unit will send a signal to the circuit breakers trip actuator. This will cause the circuit breaker to open, which is why this test is typically performed only when a circuit breaker is withdrawn from its compartment and therefore disconnected from the switchgear bus. Contact Resistance Stationary and moving contacts are built from alloys that are formulated to endure the stresses of electrical arcing. However, if contacts are not maintained on a regular basis, their electrical resistance due to repeated arcing builds up, resulting in a signifi cant decrease in the contact’s ability to carry current. Excessive corrosion of contacts is detrimental to the breaker performance. One way to check contacts is to apply DC and measure the contact resistance or voltage drop across the closed contacts. The breaker contact resistance should be measured from bushing terminal to bushing terminal with the breaker in closed position. This is the primary circuit resistance test that was discussed in Section 8.7.2 for low-voltage power circuit breakers. This test consists of applying a DC across the closed circuit breaker contacts and measuring the voltage drop due to the contact resistance. Excessive voltage drop indicates abnormal conditions such as contact and/or connection erosion and contamination. This test is similar to the circuit breaker contact resistance measurement test described in Section 7.4.5 for medium-voltage breakers. The manufacturers of MCCBs should be consulted in order to fi nd the acceptable millivolt drop values for particular breakers being tested. It is recommended that large breakers be tested with DC of at least 100 A and smaller breakers be tested at rated (or below rated) currents. The measured values should be compared among three phases of the breaker under test, or with values of breakers of similar size or with manufacturer’s recommended values to assess whether the contacts need to be replaced or dressed. Where: \( {V_{Phase}: V_{Line-Line} , V_{Line-neutral} } \) \(\text{Phase voltage can be either Line to line or line to neutral}\) Insulation Resistance: DESCRIPTION: This test is performed at or above rated voltage to determine if there are low resistance paths to ground or between winding to winding as a result of winding insulation deterioration. PURPOSE: This test is made to verify the condition of the insulation of the circuit breaker. A minimum of 1000 V test voltage should be used for low-voltage (600 V class) breakers for making this test. It would be preferable to use a DC test voltage that is at least 1.5–1.6 times the peak AC voltage of the circuit breaker. Tests should be made between pole to ground, between adjacent poles with circuit breaker contacts closed, and between phase-to-load terminal with breaker in open position. A minimum value of 1 MΩ is considered safe to prevent a fl ashover. Resistance values below 1 MΩ should be investigated for possible trouble. Megohmmeter reading should be maintained for a period of 1 min. Make the following readings : A-phase line-side to A-phase load-side B-phase line-side to B-phase load-side C-phase line-side to C-phase load-side EATON +310 ND, CND, HND, CHND, CNDC Equipped with Type NES Digitrip RMS 310 Trip units with I2T Ramp Short Time Delay (Phase Protection) Preview-hide for budget tab File List File-1.pdf File-2.pdf File-3.pdf Ground Fault Protection: Zero Sequence: Summation Method: Zero Sequence Circuit feeders are fed through a current transformer. A zero sequence relay or circuit breaker trip unit ensures that the circuit current feeding the load will return to the source returns on those same conductors . If the current is returning to the source through a different path (usually ground), the ground-fault relay will detect this difference. If the diffrence in current exceeds a pre-determined amount for a pre-determined amount of time, the ground-fault relay will operate. Under normal operating condictions, the vector sum of the circuit currents should equal zero Phase Currents + Neutral Currents = 0 \[I_{a}+I_{b}+I_{c}-I_{n}=0\] Summation Method Direct measurement of all phase and neutral current through a protection device's current transformers is evaluated. All phase currents feeding a load should return to the source. A ground fault some where downstream will create a difference in the returning current. Phase Currents = Return Currents \[I_{a}+I_{b}+I_{c}=I_{n}\] Primary Current Test Stationary and moving contacts are built from alloys that are formulated to endure the stresses of electrical arcing. However, if contacts are not maintained on a regular basis, their electrical resistance due to repeated arcing builds up, resulting in a signifi cant decrease in the contact’s ability to carry current. Excessive corrosion of contacts is detrimental to the breaker performance. One way to check contacts is to apply DC and measure the contact resistance or voltage drop across the closed contacts. The breaker contact resistance should be measured from bushing terminal to bushing terminal with the breaker in closed position. Secondary Injectoon Testing Solid-state trip units can be tested via secondary current injection using a test set specifically designed for the device to be tested. The main shortcoming of the secondary current injection test method is that only the solid-state trip unit logic and components are tested. Unlike primary injection, this test method does not verify the current sensors, wiring, or circuit breaker current carrying components. This is the main reason why the primary injection test method has superiority over secondary injection testing. No-Trip: The protective functions of the electronic trip device can be tested, but the trip device won't send a trip signal to the circuit breakers trip actuator. This test can be performed while the circuit breaker is energized and carrying load current because a no-trip test won't cause the circuit breaker to open. Trip Mode: The protective functions of the electronic circuit are tested just like a no-trip mode test, except the trip unit will send a signal to the circuit breakers trip actuator. This will cause the circuit breaker to open, which is why this test is typically performed only when a circuit breaker is withdrawn from its compartment and therefore disconnected from the switchgear bus. Contact Resistance Stationary and moving contacts are built from alloys that are formulated to endure the stresses of electrical arcing. However, if contacts are not maintained on a regular basis, their electrical resistance due to repeated arcing builds up, resulting in a signifi cant decrease in the contact’s ability to carry current. Excessive corrosion of contacts is detrimental to the breaker performance. One way to check contacts is to apply DC and measure the contact resistance or voltage drop across the closed contacts. The breaker contact resistance should be measured from bushing terminal to bushing terminal with the breaker in closed position. This is the primary circuit resistance test that was discussed in Section 8.7.2 for low-voltage power circuit breakers. This test consists of applying a DC across the closed circuit breaker contacts and measuring the voltage drop due to the contact resistance. Excessive voltage drop indicates abnormal conditions such as contact and/or connection erosion and contamination. This test is similar to the circuit breaker contact resistance measurement test described in Section 7.4.5 for medium-voltage breakers. The manufacturers of MCCBs should be consulted in order to fi nd the acceptable millivolt drop values for particular breakers being tested. It is recommended that large breakers be tested with DC of at least 100 A and smaller breakers be tested at rated (or below rated) currents. The measured values should be compared among three phases of the breaker under test, or with values of breakers of similar size or with manufacturer’s recommended values to assess whether the contacts need to be replaced or dressed. Where: \( {V_{Phase}: V_{Line-Line} , V_{Line-neutral} } \) \(\text{Phase voltage can be either Line to line or line to neutral}\) Insulation Resistance: DESCRIPTION: This test is performed at or above rated voltage to determine if there are low resistance paths to ground or between winding to winding as a result of winding insulation deterioration. PURPOSE: This test is made to verify the condition of the insulation of the circuit breaker. A minimum of 1000 V test voltage should be used for low-voltage (600 V class) breakers for making this test. It would be preferable to use a DC test voltage that is at least 1.5–1.6 times the peak AC voltage of the circuit breaker. Tests should be made between pole to ground, between adjacent poles with circuit breaker contacts closed, and between phase-to-load terminal with breaker in open position. A minimum value of 1 MΩ is considered safe to prevent a fl ashover. Resistance values below 1 MΩ should be investigated for possible trouble. Megohmmeter reading should be maintained for a period of 1 min. Make the following readings : A-phase line-side to A-phase load-side B-phase line-side to B-phase load-side C-phase line-side to C-phase load-side EATON +310 ND, CND, HND, CHND, CNDC Equipped with Type NES Digitrip RMS 310 Trip units with I2T Ramp Short Time Delay (Phase Protection)

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Preview

Zero Sequence

Circuit feeders are fed through a current transformer. A zero sequence relay or circuit breaker trip unit ensures that the circuit current feeding the load will return to the source returns on those same conductors . If the current is returning to the source through a different path (usually ground), the ground-fault relay will detect this difference. If the diffrence in current exceeds a pre-determined amount for a pre-determined amount of time, the ground-fault relay will operate.

Under normal operating condictions, the vector sum of the circuit currents should equal zero

Phase Currents + Neutral Currents = 0

\[I_{a}+I_{b}+I_{c}-I_{n}=0\]

Summation Method

Direct measurement of all phase and neutral current through a protection device's current transformers is evaluated. All phase currents feeding a load should return to the source. A ground fault some where downstream will create a difference in the returning current.

Phase Currents = Return Currents

\[I_{a}+I_{b}+I_{c}=I_{n}\]

Primary Current Test

Stationary and moving contacts are built from alloys that are formulated to endure the stresses of electrical arcing. However, if contacts are not maintained on a regular basis, their electrical resistance due to repeated arcing builds up, resulting in a signifi cant decrease in the contact’s ability to carry current. Excessive corrosion of contacts is detrimental to the breaker performance. One way to check contacts is to apply DC and measure the contact resistance or voltage drop across the closed contacts. The breaker contact resistance should be measured from bushing terminal to bushing terminal with the breaker in closed position.

Secondary Injectoon Testing

Solid-state trip units can be tested via secondary current injection using a test set specifically designed for the device to be tested. The main shortcoming of the secondary current injection test method is that only the solid-state trip unit logic and components are tested.

Unlike primary injection, this test method does not verify the current sensors, wiring, or circuit breaker current carrying components. This is the main reason why the primary injection test method has superiority over secondary injection testing.

No-Trip:

The protective functions of the electronic trip device can be tested, but the trip device won't send a trip signal to the circuit breakers trip actuator. This test can be performed while the circuit breaker is energized and carrying load current because a no-trip test won't cause the circuit breaker to open.

Trip Mode:

The protective functions of the electronic circuit are tested just like a no-trip mode test, except the trip unit will send a signal to the circuit breakers trip actuator. This will cause the circuit breaker to open, which is why this test is typically performed only when a circuit breaker is withdrawn from its compartment and therefore disconnected from the switchgear bus.

Contact Resistance

This is the primary circuit resistance test that was discussed in Section 8.7.2 for low-voltage power circuit breakers. This test consists of applying a DC across the closed circuit breaker contacts and measuring the voltage drop due to the contact resistance. Excessive voltage drop indicates abnormal conditions such as contact and/or connection erosion and contamination. This test is similar to the circuit breaker contact resistance measurement test described in Section 7.4.5 for medium-voltage breakers. The manufacturers of MCCBs should be consulted in order to fi nd the acceptable millivolt drop values for particular breakers being tested. It is recommended that large breakers be tested with DC of at least 100 A and smaller breakers be tested at rated (or below rated) currents. The measured values should be compared among three phases of the breaker under test, or with values of breakers of similar size or with manufacturer’s recommended values to assess whether the contacts need to be replaced or dressed.

Where:

\( {V_{Phase}: V_{Line-Line} , V_{Line-neutral} } \) \(\text{Phase voltage can be either Line to line or line to neutral}\)

Insulation Resistance:

DESCRIPTION:

This test is performed at or above rated voltage to determine if there are low resistance paths to ground or between winding to winding as a result of winding insulation deterioration.

PURPOSE:

This test is made to verify the condition of the insulation of the circuit breaker. A minimum of 1000 V test voltage should be used for low-voltage (600 V class) breakers for making this test. It would be preferable to use a DC test voltage that is at least 1.5–1.6 times the peak AC voltage of the circuit breaker. Tests should be made between pole to ground, between adjacent poles with circuit breaker contacts closed, and between phase-to-load terminal with breaker in open position. A minimum value of 1 MΩ is considered safe to prevent a fl ashover. Resistance values below 1 MΩ should be investigated for possible trouble.

Megohmmeter reading should be maintained for a period of 1 min. Make the following readings :

A-phase line-side to A-phase load-side
B-phase line-side to B-phase load-side
C-phase line-side to C-phase load-side

EATON +310

ND, CND, HND, CHND, CNDC Equipped with Type NES Digitrip RMS 310 Trip units with I2T Ramp Short Time Delay (Phase Protection)

Preview-hide for budget tab

File List

File-1.pdf
File-2.pdf
File-3.pdf