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Understanding the Purpose of Electrical Relays, Their Working and Selection

By Anzar Hasan, Chief Inspector

Electrical relays are simple switches that basically have an electromagnet and set of contacts, which are operated both electrically and mechanically. The main operation of a relay comes in places where only a low-power signal can be used to control a circuit. It is also used in places where only one signal can be used to control a lot of circuits. Relays are safety devices that protect a circuit from advertent operation or an electrical fault in the circuit. Advertent operation could be described as the usage of Relay 25 used in the generator circuit in power stations. To reduce the possibility of catastrophic mechanical failure of the generators from inadvertent attempts by operators to synchronize the generators out of phase, a synchronization check relay, device number 25 is installed. If it is not installed a recommendation is warranted.

The relay primarily has four main components:

• Electromagnet
• Movable Armature
• Switch point contacts
• Spring

IEEE Device Numbers
1 Master Element
2 Time Delay Starting or Closing Relay
3 Checking or Interlocking Relay
4 Master Contactor
5 Stopping
6 Starting Circuit Breaker
7 Rate of Change Relay
8 Control Power Disconnecting Device
9 Reversing Device
10 Unit Sequence Switch
11 Multi-function Device
12 Overspeed Device
13 Synchronous-speed Device
14 Underspeed Device
15 Speed – or Frequency, Matching Device
16 Data Communications Device
17 Shunting or Discharge Switch
18 Accelerating or Decelerating Device
19 Starting to Running Transition Contactor
20 Electrically Operated Valve
21 Distance Relay
22 Equalizer Circuit Breaker
23 Temperature Control Device
24 Volts Per Hertz Relay
25 Synchronizing or Synchronism-Check Device
26 Apparatus Thermal Device
27 Undervoltage Relay
28 Flame detector
29 Isolating Contactor or Switch
30 Annunciator Relay
31 Separate Excitation
32 Directional Power Relay or Reverse Power Relay
33 Position Switch
34 Master Sequence Device
35 Brush-Operating or Slip-Ring Short-Circuiting Device
36 Polarity or Polarizing Voltage Devices
37 Undercurrent or Underpower Relay
38 Bearing Protective Device
39 Mechanical Condition Monitor
40 Field (over/under excitation) Relay
41 Field Circuit Breaker
42 Running Circuit Breaker
43 Manual Transfer or Selector Device
44 Unit Sequence Starting Relay
45 Abnormal Atmospheric Condition Monitor
46 Reverse-phase or Phase-Balance Current Relay
47 Phase-Sequence or Phase-Balance Voltage Relay
48 Incomplete Sequence Relay
49 Machine or Transformer, Thermal Relay
50 Instantaneous Overcurrent Relay
51 AC Inverse Time Overcurrent Relay
52 AC Circuit Breaker
53 Exciter or DC Generator Relay
54 Turning Gear Engaging Device
55 Power Factor Relay
56 Field Application Relay
57 Short-Circuiting or Grounding Device
58 Rectification Failure Relay
59 Overvoltage Relay
60 Voltage or Current Balance Relay
61 Density Switch or Sensor
62 Time-Delay Stopping or Opening Relay
63 Pressure Switch
64 Ground Detector Relay
65 Governor
66 Notching or Jogging Device
67 AC Directional Overcurrent Relay
68 Blocking Relay
69 Permissive Control Device
70 Rheostat
71 Liquid Level Switch
72 DC Circuit Breaker
73 Load-Resistor Contactor
74 Alarm Relay
75 Position Changing Mechanism
76 DC Overcurrent Relay
77 Telemetering Device
78 Phase-Angle Measuring Relay or “Out-of-Step” Relay
79 AC Reclosing Relay
80 Flow Switch
81 Frequency Relay
82 DC Reclosing Relay
83 Automatic Selective Control or Transfer Relay
84 Operating Mechanism
85 Communications, Carrier or Pilot-Wire Relay
86 Lockout Relay
87 Differential Protective Relay
88 Auxiliary Motor or Motor Generator
89 Line Switch
90 Regulating Device
91 Voltage Directional Relay
92 Voltage and Power Directional Relay
93 Field Changing Contactor
94 Tripping or Trip-Free Relay
95 For specific applications where other numbers are not suitable
96 Busbar Trip Lockout relay
97 For specific applications where other numbers are not suitable
98 For specific applications where other numbers are not suitable
99 For specific applications where other numbers are not suitable

Suffixes & Prefixes

Suffix letters or numbers may be used with device numbers. For example, the suffix “ N” is used if the device is connected to a neutral wire, hence 59N is a relay used for protection against neutral displacement & suffixes X, Y, Z are used for auxiliary devices. Similarly, the “G” suffix is used to denote a “ground”, hence “51G” is a time overcurrent ground relay. The “G” suffix can also mean “generator”, hence “87G” is a generator differential relay while “87T” is a transformer differential relay. “F” can denote “field” on a generator or “fuse”, as in the protective fuse for a transformer.

Suffix numbers are used to distinguish multiple “same” devices in the same equipment such as 51-1 & 51–2. Device numbers may be combined if the device provides multiple functions, such as instantaneous & inverse time overcurrent relay denoted as 50/51.

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Five Reasons Why BPC is the #1 Choice for Boiler Inspections

For many states, boiler and pressure vessel inspections are basic requirements for insurance. Here at Boiler & Property Consulting, we’re proud to be a leader in jurisdictional boiler and pressure vessel inspections.

Here are five reasons why we’re number one:

1. Expertise: pressure equipment inspection is a major requirement for most business owners. We provide the highest level of expertise for any needed inspections.

Each of our boiler inspectors have years of experience and are certified through the National Board of Boilers and Pressure Vessel Inspectors. We have provided thousands of businesses with inspection services over the years, and one of our basic requirements is that all of our jurisdictional boiler inspections must be carried out by commissioned officers.

2. Destructive Potential: At BPC we know the importance of the inspection process because of the destructive potential of pressure vessels and boilers. These can endanger the lives of employees and customers if not properly maintained and inspected. With our wealth of experience inspecting these pressure vessels, we have gained a comparative advantage in the field.

3. Network of Certified Inspectors: BPC has a large number of certified inspectors licensed by the local jurisdiction where they render these services. Our inspectors have national certifications so their skill and competency level is not in doubt as they are recognized by local and national agencies.

4. Regulatory Compliance: At BPC we align the inspection needs of our customers with the laws of their states in order to keep them on the right side of the law. Whether it’s a small, medium or large-scale business, BPC meets any and all of our customers’ inspection needs.

We are aware of the consequences of not having the correct inspection requirements and help our clients avoid paying fines or having their operation shut down.

5. Passion For Excellence: At BPC, excellence is our top priority in order to succeed in providing safety and satisfaction to all of our clients. We derive passion and pride in being the preferred pressure vessel and boiler equipment inspection service. We have worked very hard to create an excellent reputation in the industry as evidenced by our current run of 9 straight months with the lowest percentage of overdue objects.

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SEVEN months in a row!

BPC_WebBadge_7yrssmaller

We just hit a new record! For SEVEN months in row we’ve been on JO’s lowest percentage of overdue objects list! We’re grateful for our inspectors and staff who are dedicated to providing customer service that truly sets us apart.

May JO Snapsot report

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We’re Number 1 for FIVE MONTHS in a Row!

Fifthmonthoverdues

We are very proud to announce that, for the FIFTH month in a row, we have maintained the top position for the lowest percentage of overdue objects of all of Jurisdiction Online’s users. This just illustrates how we continue to provide a level of customer service that is unmatched in the industry.

“My hat is off to our fantastic jurisdictional team that is dedicated to providing our customers with exceptional customer service,” said Venus Newton, president of BPC.

Contact us today to learn more about how we can meet your boiler inspection needs. 

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Shaft Alignment for Rotating Machinery

By Anzar Hasan
Chief Inspector

Failure to properly align shafts results in premature failure of bearings, bearing seals, couplings, and shafts that, in turn, may lead to catastrophic machine failures and process or plant shutdown resulting in a combination of property damage and loss of business. Industry sources estimate that 50 to 70%of rotating machinery failures can be attributed directly to shaft misalignment. When a driver like an electric motor or a turbine is coupled to a pump, generator, kiln drive, blowers or any other piece of equipment, it is essential that the shafts of the two pieces are aligned. Any misalignment between the two increases the stress on the shafts and will almost certainly result in excessive wear and premature breakdown of the equipment.

Since machines are three dimensional, the misalignment of the shaft centerline is addressed by determining their projected position with respect to horizontal and vertical planes. Each position has two parameters; parallel and angular. Therefore misalignment is expressed as vertical (parallel and angular) and horizontal (parallel and angular). Parallel alignment is also referred as “parallel offset”.

Methods of shaft alignment:
• Dial Indicator Methods: The most commonly used method for shaft alignment is the dial indicator method. This method is not 100% accurate, but is considered adequate for small machines. Often alignment brackets are utilized to support dial indicators. Sometimes the brackets are specially made for application.
• Laser Method. This system utilizes a laser beam source and laser beam target in the same module and uses a reflecting prism in the second module. This is a widely used and accurate method for alignments. There are commonly two types of laser beam alignment procedures – React System and Digilaser System.
• Optical Method: This requires careful set up and technique, but has the advantage that it can be used for initial alignment, determining hot alignment, and checking cold alignment offset.
• Electromechanical Spatial Resolution Method: The unique feature of this procedure is that neither shaft must be rotated in order to determine shaft position. The procedures utilized sensor and signals can be electronically nulled to a zero calibration point, which establishes an electronic straight line reference.
• Continuous Monitoring Method: Large equipment often utilizes a continuous shaft alignment monitoring system. This method utilizes unidirectional lasers mounted on the driver and the driven machine for continuous read outs. There are several configurations systems used – Permalign, Dynalign, Acculign and Indikon system that uses eddy current proximity probes.

During inspection of critical rotating equipment, it should be the practice to establish whether or not the plant has a scheduled shaft alignment program.

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From the Field: Inspection photos

One of our inspectors took these photos while doing an RA survey on some gas pipeline compressor stations. Quite an impressive operation!

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We’re Number One!

overdues chart

Have you heard?! We’re number 1! As proof of our dedication to excellent customer service, in November we had the lowest percentage of overdues of any of Jurisdiction Online’s users!

Being number one for the number of overdues is just one of the many metrics we use to ensure our service is the best in the industry. We have strict guidelines on report turnaround time as well as a 24-hour response time to emails and phone calls. In addition, all of our staff receive annual training on successful customer service techniques, as well as their technical training. It’s not unusual to have a customer tell us they didn’t know jurisdictional inspections could go so smoothly. Can you say that about your jurisdictional service provider?

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Inspection site photos

More photos from BPC inspection sites:

Fire suppression stand pipe zone 1

Fire suppression stand pipe zone 1

Emergency diesel generator for fire pumps

Emergency diesel generator for fire pumps

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From the Field: Ammonia engine room

AMMONIA ENGINE ROOM

An ammonia engine room

AMMONIA COMRESSORS CONTROL PANEL

Ammonia compressors control panel

AIR COMPRESSORS AND ASSOCIATED STORAGE TANKS

Air compressors and associated storage tanks

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From the Field: Typical Inspection Photos

Some days our inspectors see boilers that have exploded, hazards around equipment or other unsafe objects/practices. And then, on other days, everything is typical  – which is what the photos below show.

Typical high-pressure air tanks in a large manufacturing facility

Typical hi pressure air tanks in a large manufacturing facility

 

Typical hydro-pneumatic water storage tank for a mobile home park

Typical hydro pneumatic water storage tank for a mobile home par

 

Typical high-voltage transformer for an industrial facility

Typical high voltage transformer for an industrial facility

 

 

 

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Global Engineering Excellence

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