Introduction to Cutouts - SaskPower 3 Book 2/10...2. Hook the fuse link in the bo ttom jaws of the spring contact. 3. Push up and hook the top of the fuse link in the top jaws of the

March 31, 2005

S T U D E N T M A N U A L

Introduction to Cutouts

Copyright 2004 by the Training and Development Centre, SaskPower. All Rights Reserved

2 S T U D E N T T R A I N I N G M A N U A L

Prerequisites: • Single-Trip Overcurrent Protection module

Objectives: From memory, you will be able to describe the function, types and installation of the various cutouts used for overcurrent protection.

Rationale: An electrical system is susceptible to many types of overcurrent problems. Proper installation of overcurrent protection devices will keep damage to the system and customer’s equipment to a minimum. It also helps the operator to troubleshoot.

Learning Objectives• Describe the function, types and installation of cutouts.• Describe the procedure used to operate a cutout.• Demonstrate the procedure to operate a cutout.

Learning Methods• Self-learning + On-the-job• Self-learning + On-the-job• On-the-Job Demonstration and Practice

EVALUATION METHODS

• Written test• Written test• On-the-Job Evaluation

STUDENT RESOURCES

• Construction Standards Manual

Learning Steps1. Read the Learning Guide.

I N T R O D U C T I O N T O C U T O U T S 3


2. Follow the steps outlined in the Learning Guide.3. Clarify any questions or concerns you may have.4. Complete the Practice and Feedback.5. Complete the Evaluation.



Lesson 1: CutoutsLearning Objective:Describe the function, types and installation of cutouts.Learning Method:Self-learning + On-the-jobEvaluation Method:Written test

Introduction

A cutout is a piece of hardware that allows fuse links to be utilized in ahigh voltage distribution system, thus providing protection to the systemand equipment connected to it.

There are three main types of cutout found on a distribution system:

• Open link distribution cutout (grasshopper type)• Open distribution cutout (barrel type)• Enclosed distribution cutout



Open Link Distribution Cutout

The open link distribution cutout is used in locations which are at leastfive line miles from a substation or where fault current is not expectedto exceed 1,200 amps. It is most commonly found on 14.4kV ruralconstruction.

The cutout is spring-loaded and it is not enclosed. When a fuse blows,the spring action of the cutout provides an opening in the circuit.

Open Distribution Cutout

There are three main types of open distribution cutouts:

• Non-load break• Load break• Contamination

These types of cutouts incorporate the use of a hollow expulsion tube



which houses the fuse link. Each type has a specific use in certainlocations and situations.

Non-load Break Cutout

The non-load break cutout is used in locations no more than five linemiles from a substation or where fault current is expected to exceed1,200 amps. They are most commonly found on 14.4/25kV urban andrural construction.

This cutout is used to handle higher fault current and still provides costefficiency and ease of operation.



Load Break Cutout

Load break cutouts are most commonly used on RUD take-offstructures. This is due to the possibility of a charging current existingon the underground cable.

The load break cutout gives the operator the ability to break thischarging current to a maximum of 10A.

Contamination Cutout

Contamination cutouts are used in areas where airborne particles arepresent and pose a threat to the di-electric strength of insulators. Thesecontamination cutouts are specially designed to maintain the amount ofinsulation required in a specific location or situation.

A contamination cutout may be used in the following situations:

• In areas where dust particles cling to objects in the area, as theseparticles hinder the di-electric strength of the insulation on cutouts.



• In areas where small oil particles from industrial processes mightsettle on insulators nearby and form a coating on them. This coatingallows dust from the surrounding fields and roadways to stick to theinsulators and harms their di-electric strength.

• Along major roadways, since the heavy dust and salt contaminatedmist in these areas may be blown onto electrical components,covering the insulators with a conductive coating.

Enclosed Distribution Cutout



The enclosed distribution cutout is designed for up to 7,200V. It is usedprimarily on 2,400V and 4,160V systems. Although no longer installed,they are still in use.

Selection of Cutouts

There are many factors that affect the selection of cutouts. Some pointsto consider when selecting cutouts are:

• Voltage rating

CAUTION!Enclosed cutouts shall not be installed on newconstruction. Replacement of these cutouts shouldbe carried out with any alterations or conversion ofsuch structures.



• Fault current interrupting capacity• Continuous current rating• Load break capabilities• Contamination rated• Fuse rating

---Note---Fault currents are usually calculated by the engineering staff.



Lesson 2: Operation of a CutoutLearning Objective:Describe the procedure used to operate a cutout.Learning Method:Self-learning + On-the-jobEvaluation Method:Written test

Introduction

Prior to operating a cutout, a visual inspection of the cutout should bedone, checking for such things as:

• Loose connections• Chipped or broken porcelain• Blades and contacts (burns, corrosion, etc.)• Latching mechanism, alignment• Contamination

There are four main work practices to follow when operating a cutout:

• Select an appropriate hotstick.• Stand clear of grounds and any other grounded or energized

hardware on the pole. Always avoid the second point of contact.• Shield your face and eyes.• Use a firm, positive motion.

---Note---Some barrels do not fall open when the fuse blows. Checkclosely for a fuse wire hanging loose out the bottom of the barrel.

CAUTION!When operating a cutout, always be sure to:

• Clean and inspect the hotstick (eg. Telescopic fusing stickor grip-all stick).

• Inspect and wear rubber gloves if using a telescopic fusingstick.



---Note---When not in use, do not allow cutout barrels to hang upsidedown, as this affects the integrity of the barrel and the fuse.



Lesson 3: Procedure to Operate a CutoutLearning Objective:Demonstrate the procedure to operate a cutout.Learning Method:On-the-Job Demonstration and PracticeEvaluation Method:On-the-Job Evaluation



Skills Practice

1. Prior to operating cutout:

1. Test and inspect rubber gloves (if required).

2. Clean and inspect the hotstick.

3. Perform a pre-operation inspection of the cutout.

2. Open link distribution cutout:

1. Hang the appropriate fuse link on the hotstick.

2. Hook the fuse link in the bottom jaws of the spring contact.

3. Push up and hook the top of the fuse link in the top jaws ofthe spring contact with a positive motion.

4. Protect eyes and face during operation.

5. Visually inspect cutout for proper operation.

3. Open distribution cutout

1. Hang the fuse barrel on the hotstick.

2. Hang the fuse barrel in the bottom jaw of the cutout.

3. Close fuse barrel with a positive motion.

4. Protect eyes and face during operation.

5. Visually inspect cutout for proper operation.



Summary

To summarize this module, you have learned:

• Two main types of underground line design.• The advantages of an underground system.• The use of cable and apparatus identification markings.• To identify the codes and symbols used for underground mapping.

Practice Feedback

Review the lesson, ask any questions and complete the self test.

Evaluation

When you are ready, complete the final test. You are expected toachieve 100%.



Review Questions

T / F 1. A cutout provides a means of utilizing fuse links in the high voltage distribution system.

T / F 2. The cutout is designed to operate during an overvoltage condition.

3. The main types of distribution cutouts are:(a) High voltage and low voltage.(b) Open link, open and enclosed.(c) Open link, open fuse and fused.(d) Enclosed, overcurrent and open.

4. The different types of open cutouts are:(a) Contamination.(b) Load break.(c) Non-load break.(d) All of these

T / F 5. The open link distribution cutout can only be used on systems below 7,200 volts.

T / F 6. Open link distribution cutouts are often found on 14.4 kV rural construction within five miles of a substation.

T / F 7. Load break cutouts are most commonly used on RUD take-off structures.

T / F 8. Contamination cutouts are most commonly used on RUD take-off structures.

T / F 9. Dust particles hinder the di-electric strength of the insulation on cutouts.

T / F 10. Enclosed cutouts are used on new construction.

T / F 11. An open link distribution cutout is spring loaded, and when a fuse blows it provides an opening in the circuit.

T / F 12. A non-load break distribution cutout is used to handle higher fault currents.



T / F 13. An open link distribution cutout is used where the fault current is not expected to exceed 2100 amps.

14. A load break cutout gives an operator the ability to break charging current to a maximum of:(a) 10A.(b) 20A.(c) 40A.(d) 100A.

T / F 15. Contamination cutouts are specially designed to maintain the amount of insulation required in a specific location or situation.

T / F 16. Enclosed distribution cutouts are used primarily on 2400V and 4160V systems.

T / F 17. An open link distribution cutout is used where the fault current is not expected to exceed 1200 amps.

18. A visual inspection of the cutout should be done:(a) Before operating it.(b) When troubleshooting.(c) Before installation.(d) All of these

T / F 19. Stay clear of all ground wires and any other second points of contact on the pole while operating the cutout.

T / F 20. Eye protection must be worn while operating a cutout.

21. To minimize arcing when operating a cutout, open and close it with a:(a) Grip-all stick.(b) Telescoping stick.(c) Positive action.(d) Slow and steady action.

T / F 22. Some barrels do not fall open when the fuse blows.

T / F 23. Always leave cutout barrels hanging upside down when not is use.



Review Question Solutions

1. T

2. F

3. Open link, open and enclosed.

4. All of these

5. F

6. F

7. T

8. F

9. T

10. F

11. T

12. T

13. F

14. 10A.

15. T

16. T

17. T

18. All of these

19. T

20. T

21. Positive action.

22. T



23. F

Documents

Introduction to Cutouts - SaskPower 3 Book 2/10...2. Hook the fuse link in the bo ttom jaws of the spring contact. 3. Push up and hook the top of the fuse link in the top jaws of the