WHY NUMBERING LIKE 88,51 ARE USED IN ELECTRICAL CIRCUIT DIAGRAM?
You might have seen Circuit diagram with symbols named with numbers and letter prefix and suffixes. Have you ever thought why it is named in such labels? If no please read this blog. We have described some of the widely used number labels and their meaning and functions.
Numbering is done as per ANSI/IEEE (American National Standard Institute/Institute of Electrical and Electronics Engineers) standard, these standards are widely used in labeling protection devices, relays, switches, etc.
Most commonly used numbering for power circuit are 88,42,6,51,52. For Example Star-Delta starter numbering is done as 88 for Main Contactor, 6 for Starting Contactor and 42 for Running contactor as shown in figure.
In some cases, you can find alphanumeric combinations like 63A. The number 63 stands for pressure switch and A stands for Air that means Pressure switch for Air. In control diagram X, Y and Z are reserved for Auxilary Relays. Find more details about available devices above and In end will discuss important one to remember so that your circuit tracing becomes easier without looking at starter panel.
DEVICES NUMBER & FUNCTION OF THE DEVICE
| 1 | MASTER ELEMENT is a device which gives an impulse locally or from a remote point, primarily to place an equipment into operation, out of operation, or both, either immediately or after a time delay. |
| 2 | TIME DELAY STARTING OR CLOSING RELAY is a device which affords necessary time delay in placing an equipment into operation. |
| 3 | Checking or Interlocking Relay. Normally these are Push Buttons or Control Switch. |
| 4 | MASTER CONTACTOR OR RELAY is a device which makes and breaks the necessary control circuits: A. To place the equipment in operation at the proper indication of the master element and certain protective devices, and B. To take the equipment out of operation at the opposite indication. |
| 5 | STOPPING DEVICE is one which functions merely to place and hold an equipment out of operation. |
| 6 | STARTING CIRCUIT BREAKER, CONTACTOR, OR SWITCH is a device which connects machine to source of starting voltage. (The starting breaker connecting the machine to starting voltage should always be No. 6. If a compensator is present the breaker energizing the compensator is No. 6C. If one breaker has a sufficient number of poles to perform both functions, it should be designated as No. 6. In Korndorffer starting (or continuous circuit starting), No. 6 is the Y breaker and No. 6C is the breaker on the high side of the compensator.) |
| 7 | Rate of Change Relay |
| 8 | CONTROL POWER SWITCH is a hand-operated switch which connects (or disconnects) the source of control power to control bus. |
| 9 | REVERSING DEVICE. |
| 10 | UNIT SEQUENCE SWITCH is a device which changes the sequence of placing units in and out of service, in multiple unit equipments. |
| 11 | CONTROL POWER TRANSFORMER is a transformer which supplies the ac control power for operating the major ac devices. |
| 12 | OVERSPEED DEVICE is a device which functions on machine overspeed. |
| 13 | SYNCHRONOUS SPEED DEVICE is a device which indicates approximate or absolute synchronous speed. |
| 14 | UNDERSPEED DEVICE is a device which functions on a decrease in speed below synchronous or normal speed or failure of machine to rotate. |
| 15 | SPEED REGULATING DEVICE is a device for regulating the speed of a rotating machine. |
| 16 | BATTERY CHARGING CONTROL DEVICE is a device which controls the dc automatically operated devices in a battery charging equipment. |
| 17 | SERIES FIELD SHUNTING CIRCUIT BREAKER OR CONTACTOR is a device which opens or closes a shunt circuit around a machine series field. |
| 18 | ACCELERATING OR DECELERATING CONTACTOR, CIRCUIT BREAKER, OR RELAY is one which causes the operation of a succeeding device in the starting sequence after the proper conditions have been established. |
| 19 | STARTING-TO-RUNNING TRANSITION CONTACTOR OR RELAY is one which gives an impulse to main circuit devices for changing a machine from the starting to the running connections. |
| 20 | ELECTRICALLY OPERATED VALVE is a solenoid or motor operated valve either in a vacuum, air, oil, or waterline. When several different types of electrically operated valves are furnished on one equipment, they will be designated as follows: 20 A Electrically operated valve for air 20 Q Electrically operated valve for oil 20 V Electrically operated valve for vacuum 20 W Electrically operated valve for water. |
| 21 | IMPEDANCE RELAY. |
| 22 | EQUALIZER CIRCUIT BREAKER OR CONTACTOR is a device which makes equalizer connections for multiple unit equipments. |
| 23 | TEMPERATURE REGULATING DEVICE is a thermal relay which operates to hold temperature between given limits. Normally known as thermostat or temperature switch. |
| 24 | BUS-TIE CIRCUIT BREAKER, CONTACTOR, OR SWITCH is a device used to connect ac or dc buses together. |
| 25 | SYNCHRONIZING OR PARELLELING DEVICE. |
| 26 | APPARATUS THERMAL DEVICE is one which functions when given value of heating of the apparatus to which it is applied has been reached. |
| 27 | AC UNDERVOLTAGE RELAY is one which functions on a given value of ac line or control voltage. |
| 28 | RESISTOR THERMAL DEVICE is one which functions when a given value of heating of the -load indicating, load shifting, or load limiting resistors have been reached. |
| 29 | ISOLATING CIRCUIT BREAKER, CONTACTOR, OR SWITCH is a device used for completely disconnecting one circuit from another, generally during emergency operation or test. |
| 30 | ANNUNCIATOR RELAY is a nonautomatic -reset device which gives individual visual indications upon the functioning of lockout protective devices, and may also be arranged to perform the lockout function in the master control circuit. |
| 31 | SEPARATE EXCITATION DEVICE is one which connects a converter shunt field to a source of separate excitation. |
| 32 | DC REVERSE POWER RELAY is one which functions on a given value of direct-current power reversal. |
| 33 | POSITION SWITCH is one which indicates position of water wheel gate. |
| 34 | MOTOR OPERATED SEQUENCE SWITCH is a motor-operated device which fixes sequence of major devices during starting and stopping sequence. |
| 35 | BRUSH -OPERATING OR SLIP-RING SHORT CIRCUITING DEVICE is one for raising, lowering, or shifting the brushes of a machine, or for short circuiting the slip rings. |
| 36 | POLARITY RELAY is one which indicates polarity. |
| 37 | UNDERCURRENT OR UNDERPOWER RELAY is one which functions on a given minimum value of current or power flow. |
| 38 | BEARING THERMAL DEVICE is one which functions upon excessive bearing temperature. |
| 39 | FIELD REDUCING CONTACTOR is one which inserts resistance in field of machine. |
| 40 | FIELD RELAY is one which indicates presence or loss of field in a machine. |
| 41 | FIELD CIRCUIT BREAKER, CONTACTOR, OR SWITCH is a device which functions to apply, remove, or reverse a machine field. |
| 42 | RUNNING CIRCUIT BREAKER, CONTACTOR, OR SWITCH is a device which connects a machine to source of running voltage. |
| 43 | TRANSFER DEVICE is a device which transfers control of breakers, etc., from automatic to test switches, or control of equipment from manual to automatic, automatic to continuous, or performs some transfer operation other than unit sequence. |
| 44 | UNIT SEQUENCE STARTING CONTACTOR OR RELAY is one which functions to start the next available unit, in multiple unit equipment on failure or overload of normally preceding unit. |
| 45 | DC OVERVOLTAGE RELAY is one which functions on a given value of dc machine or bus overvoltage. |
| 46 | REVERSE-PHASE OR PHASE-BALANCE CURRENT RELAY OR POWER- RECTIFIER MISFIRE RELAY is one which functions on an unbalanced current condition, or on reverse phase flow of current, or on misfire of power rectifier. |
| 47 | SINGLE OR REVERSE -PHASE VOLTAGE RELAY is one which functions upon presence of correct polyphase voltage, or upon polyphase voltage of correct phase rotation, or both. |
| 48 | INCOMPLETE SEQUENCE RELAY is one which gives indication to shut down a machine and prevent its restarting if the control does not properly complete a predetermined sequence. |
| 49 | AC THERMAL RELAY is a thermal device which functions when the temperature of a-c apparatus controlled tends to decrease below or increase above the safe operating value. |
| 50 | SHORT CIRCUIT SELECTIVE RELAY is one which functions on excessive rate of rise of current and may further allow reclosing only after normal conditions have been reestablished. |
| 51 | AC OVERCURRENT RELAY is one which functions when current in an ac circuit exceeds a given value. |
| 52 | AC CIRCUIT BREAKER OR CONTACTOR. |
| 53 | EXCITER OR GENERATOR RELAY is one which indicates operating values of exciter armature voltage or current or generator voltage, or insures positive building up of exciter or generator voltage, or indicates presence of generator field. |
| 54 | HIGH-SPEED CIRCUIT BREAKER is a circuit breaker which starts to open the main circuit in 0.01 second or less on excessive rate of rise of current or on dc overload above its setting. |
| 55 | POWER-FACTOR RELAY is one which holds or indicates a given power factor on an a-c machine or system. |
| 56 | Field Application Relay |
| 57 | Short-Circuiting or Grounding Device |
| 58 | Rectification Failure Relay |
| 59 | AC OVERVOLTAGE RELAY is one which functions on a given value of ac overvoltage. |
| 60 | VOLTAGE -BALANCE RELAY is one which indicates, or functions to hold, a given voltage difference between two sources of voltage. |
| 61 | CURRENT- BALANCE RELAY is one which indicates, or holds, a given current relation between two sources of current. |
| 62 | TIME -DELAY STOPPING OR OPENING RELAY is one which affords the required time delay in the sequence of taking an equipment out of operation. |
| 63 | FLUID-PRESSURE OR FLOW RELAY is one which indicates presence, value or failure of oil, water, vacuum, or air pressure. May be used as a regulating or protective relay, or both. Also known as pressure switch. When several different types of pressure relays are furnished as one equipment, they will be designated as follows: 63A Pressure relay for air 63Q Pressure relay for oil 63V Pressure relay for vacuum 63W Pressure relay for water. |
| 64 | GROUNDING PROTECTIVE RELAY is one which functions on failure of machine insulation to ground or flashover of dc machine to ground. |
| 65 | GOVERNOR is the speed regulating device for a prime mover. Complete electrically operated governor parts are as follows: 65-A-Governor Accelerating Device (used during starting) 65-MF-Governor Fly Ball Motor 65 -ML -Governor Load Limit Motor 65 -MS -Governor Synchronizing Motor 65-S -Governor Solenoid. |
| 66 | NOTCHING RELAY is one which functions to allow only a specified number of operations of a given device, or equipment, or a specified number of successive operations within a given time of each other. Also is used to allow periodic energizing of a circuit. |
| 67 | AC POWER-DIRECTIONAL OR AC POWER-DIRECTIONAL OVER- CURRENT RELAY. |
| 68 | DC THERMAL RELAY is a thermal device which functions when the temperature of the dc apparatus controlled tends to exceed a safe operating value. Also known as Blocking or Out-of-Step Relay |
| 69 | PERMISSIVE CONTROL DEVICE. |
| 70 | ELECTRICALLY OPERATED RHEOSTAT is one used primarily to vary the resistance of a circuit in response to some contact making device. |
| 71 | DC LINE EMERGENCY CIRCUIT BREAKER OR CONTACTOR is one used to interrupt a d-c power circuit under emergency conditions. |
| 72 | DC LINE CIRCUIT BREAKER OR CONTACTOR is one used to close and interrupt a dc power circuit under normal conditions or to interrupt this circuit under emergency conditions. |
| 73 | LOAD RESISTOR CIRCUIT BREAKER OR CONTACTOR is one used to insert a step of load limiting resistance in a power circuit under abnormal or overload conditions and to shunt this step of resistance when the abnormal or overload condition has disappeared. 73-1 for breaker or contactor shunting sequence if more than one 73-2 for breaker or contactor shunting in sequence 73-3 for breaker or contactor shunting sequence 73-4 for breaker or contactor shunting sequence. |
| 74 | ALARM RELAY. |
| 75 | POSITION CHANGING MECHANISM FOR REMOVABLE CIRCUIT BREAKER UNIT. |
| 76 | DC OVERCURRENT RELAY is one which functions on a dc overload above a given amount. It may also be provided with specified dropout value so as to reclose load limiting resistor shunting circuit breaker or contactor, No. 73 for example, when the overload has disappeared. 76-1 functions with 73-1 76-2 functions with 73-2 76-3 functions with 73-3 76-4 functions with 73-4 |
| 77 | Telemetering Device |
| 78 | Phase Angle Measuring Relay |
| 79 | AC RECLOSING RELAY is a device which controls the reclosing of an ac circuit interrupter. |
| 80 | DC UNDERVOLTAGE RELAY is one which functions at a given value of dc undervoltage. |
| 81 | FREQUENCY DEVICE. |
| 82 | DC RECLOSING RELAY is one which controls the reclosing of a dc circuit interrupter. |
| 83 | SELECTIVE CONTROL CONTACTOR OR RELAY is one which selects between certain sources or conditions in an equipment. |
| 84 | Operating Mechanism |
| 85 | Communications, Carrier or Pilot-Wire Relay |
| 86 | LOCKING-OUT RELAY is one which locks out equipment on abnormal conditions. |
| 87 | DIFFERENTIAL CURRENT RELAY is one which functions on differential current of a given amount. |
| 88 | AUXILIARY MOTOR OR MOTOR-GENERATOR is used for operating equipment accessories such as pumps, blowers, etc. Also known as MAGNETIC CONTACTOR. When auxiliary motors or motor generators are furnished on one equipment for several different accessories, they should be designated as follows: No. 88 B Auxiliary motor or motor generator for blower No. 88 Q Auxiliary motor or motor generator for oil pump No. 88 V Auxiliary motor or motor generator for vacuum No. 88 W Auxiliary motor or motor generator for water. |
| 89 | LINE SWITCH is one used as a disconnecting switch in a dc power circuit. |
| 90 | REGULATING DEVICE. 90C Current regulator 90P Power regulator 90PF Power factor regulator 90V Voltage regulator 90VAR Reactive power regulator. |
| 91 | DC VOLTAGE DIRECTIONAL RELAY functions when the d-c voltage exceeds a certain amount in a given direction. |
| 92 | DC VOLTAGE AND CURRENT DIRECTIONAL RELAY is one used to give indication to close a circuit when the voltage exceeds a certain amount in a given direction, and to give the indication to open this circuit when the current exceeds a certain amount in the reverse direction. |
| 93 | FIELD-CHANGING CONTACTOR OR RELAY is one which functions to change the amount or source of excitation on a machine. |
| 94 | TRIPPING OF TRIP-FREE RELAY OR CONTACTOR is one which functions as a tripping contactor to trip out the equipment. (As a trip-free relay, it functions to prevent immediate reclosure of a circuit interrupter, in case it opens immediately upon overload, even though the original closing circuit is still held closed.) |
| 95, 97, 98, 99 | For specific applications where other numbers are not suitable |
| 96 | Transmitter |
Letters are used to define more specific function of the device. For example 63A Pressure switch for Air, Similarly when you have multiple devices of same number suffixes are added as 51-1, 51-2 , 51-n (n number to devices). Pleasse find list of prefixes and suffices used in numbering of device.
LIST OF PREFIXES & SUFFIXES
| A | Air, Automatic, Accelerating or Annuciater |
| B | Battery, Bus, Blower, Breaking of Wire |
| C | Close, Compensator, Closing Coil, Convertor, Common |
| CS | Manually operated control switch |
| D | Directional or Distance |
| E | Emergency |
| F | Forward, Frequency, Float, Fan Feeder |
| G | Ground, Generator |
| H | High, Hot, Holding, Heater, Horn |
| I | Interlock |
| J | Instant |
| L | Lamp, Low, Load, Limit, Line, Local |
| M | Motor or Manual |
| N | Normal |
| P | Power |
| PF | Power Factor |
| Q | Oil or Quick |
| R | Reverse, Raise, Remote, Resistor, Reset |
| S | Solenoid, Synchronizing or Switch |
| T | Trip or Stop, Transformer, Timer |
| V | Voltage, Vacuum |
| VAR | Reactive power |
| W | Water |
| X | Auxilary Device |
| Y | Auxilary Device |
| Z | Auxilary Device |
Designing is done with these standard with proper numbering & adding suffices for more specific function. Most Basic similar kind of devices that you can find in Local Starter Panel or Group Starter Panel are
- Contactors (88, 42, 6)
- Breaker (52)
- Overcurrent (51)
- Push Button (3). Suffices may be added such as 3C for Closing, 3T for Stopping or Trip, 3R for Resetting, 3CF & 3CR for Forward and Reverse Operation of Motor direction.
- Pressure Switch (63)
- Temperature Switch (23)
- Lamp (L). White Lamp(WL), Red Lamp(RL)
- Auxilary Relay (X, Y, Z)
- Timer (T)
CONCLUSION
This information you can find in the maker manual its similar to ANSI/IEEE standard and they design with the same. Maker manual has added a correct suffix to describe specific function of the device. It saves time in reading circuit diagram and easier for tracing only when you remember ANSI/IEEE standard of numbering devices. Apart from this practice circuit symbols.
GOOD LUCK
Missed out something? Please Comment
REFERENCE
- ANSI https://en.wikipedia.org/wiki/ANSI_device_numbers
- Standard Electrical Power Sytsem Device Function Number
LIKE POST? PLEASE SHARE
