Digital Room Sensor for HVAC System with LCD Display-Johnson Control

How to Fix the Digital Room Sensor for HVAC System?

HVAC equipment manufacturer offer now a wide range of temperature sensors for room, duct, pipe and outdoor applications. The professionals have designed the range for ease of installation, pleasing aesthetics, and more compatibility with man and machine community.

Wiring Schematic Diagram for Screw Air-Cooled Carrier Chiller

Wiring Schematic Line Diagram for Screw Air-Cooled Chiller

Though in new installation or during maintenance the wiring diagram book for carrier chillers is very essential. Considering the screw carrier chiller you will find the full schematic wiring diagram for air-cooled series-6 chiller. The model number is 30GXN, R sizes 080-528, with comfort link. This wiring guide contains the air-cooled packages screw liquid chillers. It will provide the carrier standard legend for wiring labels.

You also download the 40 pages pdf format copy of schematic wiring diagram from the link below:

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You may download the full operation, maintenance and troubleshooting manual for air and water cooled screw carrier chiller from link below:

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Safety Operation of Medium Voltage Switchgears

Hazards of operating on electrical equipment

Medium-voltage switchgear. Eaton's medium-voltage switchgear provides centralized control and protection of medium-voltage power equipment and circuits in industrial, commercial, and utility installations involving generators, motors, feeder circuits, and transmission and distribution lines. There are five kinds of hazards related to the operation of electrical equipment.

1. Electrical shock
2. Electrical burns
3. Fire and explosion
4. Heat build up
5. Mechanical hazards
6. Electrical shock

Because there may be a serious threat of flashover, shock, arcing, etc. when working in a medium voltage environment, decrease voltages tend to be handled with less admire. It need to be remembered that a voltage as low as 50 V, with a contemporary of ± 30 mA, can reason asphyxia and/or heart muscle fibrillation. The biggest hazard of strength is that live and dead apparatus are indistinguishable from each other. Therefore, equipment ought to in no way be assumed lifeless, constantly presume it's far alive. This can simplest be ascertained by checking out with the appropriate accepted tester, or by using the presence of a visible earth connection. Electricity can bounce gaps, which means that that it isn't even important to the touch a medium voltage conductor so as to get hurt. Merely approaching too near may have fatal results, therefore, it's far important to preserve close proximity distances.

1. Identify the proper substation/MSS etc.
2. Identify the best circuit breaker/ isolator.
3. Switch – open the circuit breaker/ isolator.
4. Isolate the circuit breaker with the aid of racking out/ down.
5. Test – the use of accepted voltage detector.
6. Earth – connect correctly to earth the use of correct method.

Mini sub stations (MSS) and ring fundamental panels (RMP) are opened manually the usage of the ideal working handle. The “T” off to the transformer may be furnished with a circuit breaker or fuses and opened through pushing a button on the the front of the unit. They also can be provided with an electrical remote operating device, similar to a circuit breaker. Isolate Isolution mains bodily disconnecting the equipment from all feasible resources of electrical potential by using:

1. Opening and/or putting off of fuses.
2. Opening of links.
3. Withdrawal of truck type switchgear.
4. Lock off and apply risk tags.

Security at factors of isolation:

All points of isolation ought to be locked off through the application of a non-public lock to prevent inadvertent operation of the mains or equipment. Danger tags: The use of threat tags is an essential part of the isolation process. Danger tags need to be carried out on the transfer or control equipment which has been remoted, with the intention to enable men and women to paintings on electrical equipment or conductors safely, by way of notifying people that paintings is being conducted on that piece of apparatus. 

Authorised character: 

A individual advocated via the electrical engineer or his nominee and appointed in writing with the aid of the designated individual to perform switching, isolating, testing and earthing on electric mains and apparatus, in liaison with and beneath the practise of a manipulate officer and to trouble work permits in recognize of such mains and equipment. 

Isolation technique 

The authorised person shall perform the necessary isolations, using personal locks,  onsistent with the policies and regulations. Thereafter, perform safety tests the usage of an appropriate authorised tester to make sure that the mains and/or equipment are useless and apply risk tags at all control points.

Control factor:

A function at the system where a major and/or apparatus may be switched, isolated, and earthed. When isolating, the equipment should be isolated, from all viable resources of electricity, not just energy. Therefore, we need to keep in mind the subsequent sources of hazardous strength and hazardous substances.

Hazardous strength:

Electrical, pneumatic, hydraulic, stored (springs, batteries), ability (via distinctive feature of position), heat (hot water, steam), radiation.

Hazardous substances:

Gases, vapours, liquids, dusts with the ability to purpose injury or illness, e.G. Toxic, corrosive, flammable. All plant and system need to have written methods for isolation; these approaches will set out a step by step account of the way the gadget, plant or system is to be remoted and kept secure. In the case of electrical isolation, a check for voltage should be performed with the ideal approved tester, to make sure that the mains and/or equipment are dead.

Summary

The authorised character plays the isolation in line with the regulations and regulations. Control factors need to be locked off the usage of private locks. Danger tags ought to be implemented to all factors of isolation.

The locking of manipulate factors and alertness of risk tags is crucial for a safe isolation, and isolation will not be deemed complete till those necessities are met.

Locking off of stay shutters

All stay shutters ought to be locked off with the personal lock. Cable shutters must be classed as stay shutters, as the cable might be returned fed, e.G. Open factor on a hoop, consequently, both bus bar and cable shutters should be locked off.

Test

Before applying earthing device, the conductor have to first be tested to prove it lifeless. Before the use of any approved medium voltage system it have to be physically inspected for defects. When testing medium voltage the 3 factor take a look at have to be adopted, test the tester on a known stay source or a check box furnished with the aid of the manufacturer, test all 3 levels and retest the tester.

There are several sorts of voltage testers on the market and they all have particular uses:

Voltage detector (live tester): 

Used for testing the presence of voltage. A live tester is one that has to the touch the conductor underneath take a look at if you want to decide if it's far stay or useless (it is recommended that one with audible and visible annunciation is used). These live testers are synthetic in two distinct types – S and L. S kind to be used on switchgear. L type for use on overhead lines.

Phase comparator/phasing sticks (live tester):

Used to test that circuits are in segment with every other. A phase comparator have to be used for phase contrast and now not voltage detection.

Phasing in of ring feeds

It is vital to segment in medium voltage system prior to energising cable circuits, to make certain the appropriate segment rotation whilst cable systems are maintained and extended. Electrical phasing have to be carried out while:

1. New system is installed, which necessitates breaking into a ring feed, e.G. New substations.
2. After the repair to any cable which forms part of a hoop feed.
3. Whenever a cable which forms a part of a ring feed is terminated.
4. An existing cable (to be again to service) is being joined and/or terminated.

Voltage detector (proximity tester):

Used on overhead lines. This tester does now not must come into contact with the conductor below take a look at to determine if it's far live or dead, it detects the magnetic field and consequently best works on naked and unscreened conductors.

There are no test facilities to test the cable is useless before earthing on an MSS/RMP, however, maximum modern units are supplied with LEDs, indicating if the cable is live or useless and these should be used as a guideline whilst operating. They additionally have the ability for doing electrical phasing on the front of the unit, using a multimeter. MSS/RMPs do have take a look at points, however these are for checking out the cable as soon as it's been earthed and consequently get admission to can only be won to them once the cable has been earthed.

Earthed

Connected to the overall mass of earth in such a way as to make sure always an immediate safe discharge of power. There are several special forms of earthing methods: fundamental earthing, earthing carriage, earthing truck, and transportable earths. Integral earthing is designed into the circuit breaker and no outside attachments should be implemented to the circuit in order to earth it.

Earthing bus bars

When earthing a bus bar all viable assets of deliver must be isolated. Therefore:

All far flung ends ought to be switched, isolated, locked off and threat tags carried out.

All nearby circuit breakers must be switched, remoted, locked off and hazard tags applied.

Test with an accepted voltage detector.

Apply no less than one earth. Portable earthing device A p p l i c a t i o n o f p o r t a b l e e a rt h i n g system:

1. The mains and/or equipment to be earthed ought to be tested with an authorised voltage detector to ensure that it's far dead.
2. Check the condition of the portable earths
3. Securely connect the flexible cause an earth bar or earth conductor FIRST.
4. Using an earth or hyperlink stick touch every segment of the mains and/or apparatus to be earthed.
5. Clamp onto every section.
6. When casting off the portable earths theearth connection need to be eliminated last.
7. Care must be taken to make certain exact tight connections. It is the authorised character’s responsibility to ensure that all portable earths are removed earlier than energising the circuit.

Interlocs

All circuit breakers and MSS/RMPs have mechanical interlocks, for example, you can't rack a circuit breaker out if it's miles closed, you'll no longer have the ability to region an earth on an RMP unless it's been opened first. However, they're no longer interlocked with each other and it is feasible to earth a live cable. To this cease, the ideal oprating method ought to be accompanied and the authorised individual need to ask himself, earlier than operating, what impact will the operation I perform have at the rest of the device – for every action there's a reaction! The following is a listing of a number of the matters to remember earlier than working:

Switch (open)

Will any deliver be misplaced? If so, can I reroute the supply (shift open point on the ring, or shift load onto any other circuit).

1. If load has been shared with some other circuit, make sure that that circuit can convey the blended load.
2. If load has been shared with any other circuit, ensure that that circuit has picked up load before starting the circuit breaker.
3. Once the circuit breaker has been opened, take a look at the other circuit has picked up the full load.
4. Can the circuit breaker be opened remotely, if not what PPE is required?
5. On a MSS/RMP the LEDs may be used to see if supply is lost to different circuits and to test if the circuit is lifeless.

Isolate

Have all 3 phases on the circuit breaker opened?

Before racking out/down a circuit breaker, it is right practice to test all three phases are now not drawing load, this could be done via the usage of the ammeter selector switch, if one is fitted.

Test

Is the tester suitable to be used at the system? E.G. correct kind and voltage rating.

Is the tester in exact circumstance?

There are no check facilities (NTF) on a MSS/RMP prior to earthing.

Earth

Is the opposite facet of the circuit opened and isolated or earthed?

When reinstating the circuit

Remove earths

There is no electrical tripping in the earth function on a circuit breaker, so the circuit breaker needs to be tripped manually.

Close

Has the earth been eliminated on the faraway stop?

1. Has the far off end been made safe? E.G. Has the area been checked after paintings that there no tools were left inside the operating place. Have employees been warned it's miles now not safe to work within the place. Have portable working earths been eliminated etc.
2. Has the remote cease been secured? E.G. Has it been isolated and locked off?

Work allows

Written authorisation for work to be accomplished on electrical mains and/or apparatus. Once the circuit has been made safe for paintings as above, the authorised person will difficulty a medium voltage work permit for work to be performed on the remoted mains and/ or equipment. It is crucial when issuing a work permit the following interaction with the character in fee is executed:

1. Give explicit instructions to the individual in price of the paintings regarding the paintings to be performed and the secure limits of the workplace and make certain that this is understood.
2. Show the person in price the manage points and permit him/her to location their non-public lock at the manage point.
3. Earth or show the mains/equipment dead on the worksite.

When receiving the work permit returned on the place of job from the person in fee, the authorised person is answerable for acquiring confirmation that each one persons are clear of the mains and/or equipment and that each one non-public running earths implemented at some point of the work were removed.

How Carry Out the Quality Inspection Test for Electrical Installation?

Quality Inspection Test is Obligation to Handover the Electrical Installation Project to the Client

Visual Inspection Test, Insulation Resistance Test, Hi-pot or High Voltage Injection Test, Primary Current Injection Test, Secondary Current Injection Test and Metering Current Transformer Polarity Test is the significant testing and commissioning requirements for any electrical installation. Also, Safety and Risk Control is the first priority task to supervisor or project manager to carry the project minimizing the hazards.

Visual Inspection Test:

Visual inspection test generally jointly with customer will be carried out at equipment installation site on the LV switchboard, where physically check to :)

• Checking the layout of fitted components as per requirement following the local or international standards; 
• Checking the overall dimension and sub-dimension  for each installed equipment like- switchboard, size of busbars, cable & cable trench, earthing conductors and location of feeder entry and takeoff point;
• Checking and verify with client's requirement the product brand and origin, model, and circuit identification of installed components like- breakers, CT-PT (Current Transformers-Potential Transformer), fuses, ammeters, voltmeters, power meters and protection relays etc;
• Checking overall paint, coating and galvanizing work, door and cabinet locking device, door gasket, door hinges, door cut-out holes as per required IP ingress protection rating;
• Checking the busbar, cable & conductor termination point, all nut-bolt tightening; the marking & identification ferules , busbar safety clearance and phase gap between exposed live conductor, base angle bar and plinth;
• Checking the labels & markings, name plate and phase identification as safely and correctly.

Insulation resistance Test

Carry out insulation resistance test using 500V meggar for LV (Low Voltage) equipment phase to earth, neutral to earth, phase to neutral and phase to phase to measure the insulation resistance with all breakers or switches in ‘ON’ positions.

All reading must be recorded in approved record sheet and finally produce a  Quality Assurance Test Report.

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Megger Range Selection Criteria of IR Test:

Insulation testers with test voltage of 500, 1000, 2500 and 5000 V are available. The recommended ratings of the insulation testers are given below:

Voltage Level	IR Tester
650V	500V DC
1.1KV	1KV DC
3.3KV	2.5KV DC
66Kv and Above	5KV DC

High Voltage Injection or Hi-Tot Test

Hi-Pot or high voltage test normally uses to check in any leakage or  weak point near to leakage, generally applied test voltage is three times of rated voltage. Low voltage switching equipment high voltage test carried out using 500V meggar test between each stressed phase and all other phase connected to exposed conductive parts with all breakers in ‘ON’ positions.

Applying 2.5kV AC voltage between each stressed phase and all other phase connected to exposed conductive parts of low voltage equipment for 60 seconds and measure the leakage current.

Primary Current Injection Test

The primary current injection test procedure generally followed as- 

01. Temporarily short for testing purpose all phases the R, Y, B and neutral N primary bars on one side of the protection CT (current transformers).

02. Connect the primary injection test set on R-phase and neutral N on primary bars on the other side of the current transformers.

03. Secondary current is monitored connecting an ammeter to the R-phase of CT.

04. Spill current is monitored connecting a milli-ammeter to the earth-fault relay current coil. 

05. Spill current is recorded separately as injecting 50% and 100% of the CT ratio through the primary bars. Also at the same time, record the secondary current of the R-phase respectively.

06. All test from 1 to 5 should be repeated for all other B & Y phases and test data should be recorded in quality assurance data sheet.

Secondary Current Injection Test

The secondary current injection test procedure generally followed as- 

01. Selecting the current plug setting of IDMTL relay to the rated current of 5A and TMS of 0.1 for 3/10 characteristic.

02. Then inject secondary current of 5A to R-phase and adjust pickup current to 5A.

03. Then one by one inject 10A, 15A and 25A to R-phase and record on record sheet the tripping time respectively. Noted that the standard timing should be within+30% and -10%.

04. accordingly select the proposed current setting and adjust the pickup current.

All test from 1 to 4 should be repeated for all other B & Y phases and test data should be recorded in quality assurance data sheet. 
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 Safety & Risk Control During Test

Safety Arrangement must comply all safety and risk control procedure, using the following four step risk management process may allow to consider risks associated with managing electrical risks in the testing workplace:

1. Identify the hazard problem.
2. Risk assessment or determine the level of risk to testing places and others as a result of the problem.
3. find the risk control procedure or decide what needs to be done about the problem.
4. Make sure that all are working as planned.

All test should be carried out following the procedure as below-

01. Safety barriers will be installed surrounding the area where the testing work is going to be carried out.

02. Tag in/ Tag out and sufficient danger signs will be hanged to warn the people who approach the testing area.

03. Visible warning lamp or flashing light should be confirm during supplying power to the board for testing

(D) First aid box and basic fire fighting  equipment will be placed for emergency usage at testing area.

EXCELLENT WORKSHOP PRACTICE AND HOUSEKEEPING REDUCE ACCIDENTAL MISTAKE IN WORK

Excellent workshop practice and outstanding housekeeping in maintenance and construction department can reduce accidental mistake in work.

Lack of workshop practice and ignored housekeeping causes most of the accidental incidence in workplace. On the other hand good workshop practice and housekeeping can reduce chances of mistake in working site.

Workshop is a special room or building in which some goods are repaired or manufactured, a group of people engaged cumulatively on a particular character of job, and safety is everyone’s responsibility to ensure.

Accordingly an outstanding housekeeping and record-keeping practice facilitates productive work and hazard free organization.

Our focus as regarding workshop practice and housekeeping is not on definitional, but we just want to figure out some key point to practice before start our everyday works. So, here followed some tips to practice excellent workshop practice-

How ensure excellent workshop practice in Maintenance & Construction site?

First of all Workshops must be kept tidy and free from waste materials, rubbish, etc;

Gangways shall be clearly marked and kept free from any obstructions;

Each machine shall have its own clearly marked boundary and available area;

Machineries what produce sharp particles and metal chipes must be guarded or screened to prevent particles and chippings from machines striking persons on adjacent machines or in the walk ways;

All rubbish shall be placed in bins or drums, which shall be emptied regularly. Oil rags shall not be allowed to accumulate because of the risk of auto-ignition;

High presser compressed air shall not be used to blow sawdust, filings, etc;

Where overhead gantry cranes are installed, they shall only be operated by competent persons. They shall be fitted with travel alarms;

Welding areas shall be fully screened to prevent the UV light affecting non-involved workmen;

Oil and lubricant spillages shall be cleaned up immediately;

Fire protection equipment must not be obstructed and must be in good working condition. Eye protection must be worn when operating workshop equipment. Hearing protection must also be worn when operating noisy equipment.

Restriction to use compressed air in workshop practice

The use of compressed air for cleaning or drying shall only be permitted when other more acceptable methods are impracticable;

Under normal conditions the maximum pressure permissible for such purposes shall be 0.7 bar/ 10 psi. air-lines shall be fitted with an appropriate pressure regulator;

Under no conditions shall compressed air be used to blow dust or dirt off an employee skin or clothing, or for cooling purposes;

Any person handling compressed air shall wear eye protection;

Compressed air hoses used for clothing or drying shall be fitted with a proper nozzle which includes an on/off valve;

Under no circumstances, except in an emergency, shall the air supply be cut off by kinking the hose;

Hose coupling shall be fitted with pins or other means to prevent accidental disconnection;

Horseplay with compressed air is extremely dangerous and is prohibited.

Instructions for housekeeping keep away hazardous incident

Waste materials and rubbish are a fire risk and an accident hazard. They shall be kept to an absolute minimum and placed in either scrap or rubbish containers;

Waste containers shall be located at suitable place on site;

Do not allow oily rags to accumulate, they can ignite spontaneously;

Spilled liquid shall be wiped immediately;

Waste food should not be mixed with dry refuse. Food bin should be tightly fitting lids and be emptied not less than once per day;

Do not obstruct walkways, roadways, gangways or stairways;

Do not bring more material from the materials yard than is needed. It gets in the way and leads to waste;

Return surplus materials to the material yard or store;

Ensure that tools are kept in tool boxes when not in use;

All work areas must be kept orderly and clean on a daily basis.

Yes guy; already gathered lots of knowledge about excellent workshop practice and outstanding housekeeping to reduce accidental mistake in workplace. Now it’s your turn to materialize your knowledge by practiing in everyday work.