ANSI Codes Description or undrestanding

After posting All ANSI device codes, I thought, If there is short description/definitions for each device, it will be good for all.

So I will start in the sequences as I have posted in Device codes.

1-      MASTER ELEMENTS:

Any initiating Device will be term as master element.  Like, Control Switches, voltage relays, Current Sensors etc. this device serves may be directly or it will operate some other protective device and will place equipment in or out of protection.

Examples:

1)      Consider TNC switch ( Trip-Neutral-Close) to act as breaker control switch. So TNC is master element for Breaker.

2-      Time Delay Relay or Closing Relay:

The Device which provides required time delay during switching application or relaying application, before or after the point of operation is termed as Time Delay Relay or Closing Relay.

Examples:

1)      Consider Overvoltage Protection. Generally devices are designed to operate satisfactorily from 85% to 110% of voltage levels. So in case of overvoltage it is necessary to not to trip breaker instantly. After manufacturer specified limit reach for max operating voltage ( say 105% or 110%) circuit will be monitored through overvoltage relay. And as soon as voltage will rise it will wait for pre-defined time delay, up to what equipment may not get damage.

And after that completion of time, Time delay relay will give command to breaker for overvoltage tripping.

Consider capacitor bank, in which it is necessary to avoid fault tripping or alarming condition during inrush, system ground fault, switching of nearby equipment or non-simultaneous pole operation of the energizing switch. So during all of these condition breaker should not be tripped. So we have to allow a time delay slightly longer than the fault clearing time of upstream breaker. Generally, almost for these applications time delay will be taken nearly 0.1 sec.

2)      Time delay relay will also termed as closing relay. Let’s have a look how it termed as closing relay. Consider a pumping station having 3 pumps. Each pump is associated with inlet and outlet valve.

Now pump no. 1 must be start after opening of inlet valve and closing of outlet valve. Now there will be a limit switch to sense the position of valve. And pump 1 is closed. Now inlet valve of pump 2 will be give command after 1 minute of starting period of pump 1. And so on pump 3 depends on pump 2. So in this condition, time delay relay is used as a permissive action for closing purpose. So it can term here as closing relay.

3) - Checking or Interlocking relay:

                The relay which will operate in response with other device/pre-defined condition, and will allow to close/proceed or to open/stop, will be termed Interlocking relay. Also it will operate not to interlock but just to check the condition, then it will termed as Checking relay.

Example:

For Example viewed above on time delay relay, consider same example here. As Pump 1 is dependent on limit switch of inlet and outlet valve, this limit switch can be termed as Interlocking relay/device.

Similarly, If this limit switches has been used for indication also, then it will termed as checking device/relay.

Consider another example of switching assembly; of 2 incomer and 1 bus coupler (tie) breaker system. Now there is predefined condition, in which any of the two breakers can be closed at a time, and if 3^rd breaker will be close on the same time, any of the one or both breakers closed must turned to open condition. For this purpose we need to use breaker status via. Aux. switches or via Contact multiplier relay. So in this case, it will term as interlocking relay.

As this relay checks the condition of another breaker it can also be termed as checking relay.

4) – Master Contactor:

                It is a device controlled by master element. (ANSI CODE 1)

                Also It can be controlled &/or operates by other equivalent device &/or Protective as well as permissive devices, which are necessary to make an equipment into/out of operation by closing a control circuit or breaking of control circuit, in normal operation &/or faulty (abnormal conditions).

Example:

                To start a motor through starter, we must have to energize first, a main contactor, which can either closed by PB/closing contact of controlling switch. Or it can be activated by command from a relay or permissive devices. So this main contactor is Master Contactor, as it can be energized/de-energized by master element like, TNC or PB etc.

5- Stopping Device:

                It is a control device which primarily used to shutdown equipment or held it out of operation. Keep in mind that this device is entirely different that of lockout device (86), as lockout device will activate only for abnormal conditions.

Example:  Emergency Pushbutton.

6- Starting Circuit Breaker: 

                It is a device which will connects a machine to its source of starting voltage.

Example:  Consider SLD as shown below. In this SLD when MCCB 2 and MCCB3 will be switched on than only Motor 2 and Motor 3 will connects to its source of starting voltage. When MCCB1 will be switched on Motor 1 will connect to its source of starting voltage. So in this view MCCB1, MCCB2 & MCCB3 are starting Circuit breaker for Motor 1, Motor 2, and Motor 3 respectively.

Consider another example, as shown in SLD below. T-1 is connected to Generator through 52-1 CB.  Generator is voltage source for T1. So 52-1 CB is starting CB for T-1. Similarly T-1 is starting voltage source for T-2 is connected to T-1, via 52-2. So 52-2 is starting CB for T-2.

Consider as shown in SLD, T-2 is feeding 1 transmission line and 2 industrial loads. Industrial load one and two are connected to T-2 , via 52-5 & 52-6 respectively. So, 52-5 & 52-6 are starting CB for Industrial load 1 & Industrial load 2.

And transmission line is fed by T-2 via 52-4 CB. So 52-4 is starting CB for transmission line.

7- Anode Circuit Breaker:

               

                It is a device used in anode circuit of power rectifier, for primary purpose of interrupting the rectifier circuit if an arc-back should occur.

8- Control Power Disconnecting Device:

               

The device which will disconnect or connect source of control power to bus or/& Equipment will be termed as Control Power disconnecting device.

Examples:

               

Consider Two Simple circuits shown in above schematics.

Fig 1 shows, two fuses connected to aux. supply source, which can connect or disconnect 52x relay from aux. supply, and make it into operation or out of operation.

Fig. 2 Shows, MCB has been used for disconnecting or connecting of 52X relay.

In both cases Fuse/MCB has been denotes by 8- which indicates they are acting as control power disconnecting device. D- indicates used for DC supply. Similarly 8A or 8AC will denotes for AC supply control power disconnecting device.

9- Reversing Device:

                It is a device that is used to reverse a machine field or will perform any other reversing function.

10- Unit Sequence Switch:

                It is a switch that is used to change a sequence of operation or operating equipment. So that units may be placed in & out of operation in multiple unit equipment.

Example: Consider 3 breaker systems for switchgear, comprising, 2 Incomer & 1 Bus-coupler (Tie) breaker System.

As it is desired to run any of two breakers at a time, and if 3^rd breaker gets close, any one of two breakers or both breakers must have to trip in order to avoid mal operation. This can be achieved by some programmed logic or by manually operated switch.

Take an example of manually operation. I/C 1 & I/C 2 is in closed position. Now due to certain reason it is necessary to transfer all load of I/C 1 on I/C 2 , and after that I/C 1 has to shut down for maintenance purpose. So we need to close a tie breaker, and we must have to open I/C 1 breaker.

Now as tie breaker is closed, and all load has been transferred to I/C 2 breaker, it is necessary to shut down I/C 1.  This can be achieved by 3 position selector switch, which will be located in tie breaker, (+T10) . +T denotes located in tie breaker. And 10 stands for 3 position selector switch.

3 positions will be I/C 1, I/C 2 & Tie. So towards the position switch will move, that breaker will get close. So to shut down I/C 1, this switch knob will move towards I/C 1 position. NO contact of this switch has been used in series with, Trip coil of every breaker. So, as we have moved to wards I/C 1 position, NO contact of this switch, in I/C 1 circuit will become NC and will trip coil will get energized, and breaker will trip, with some predefined time delay.

Take a look on simple schematic shown below, for clear view of operation.

As shown in scheme of IC 1, it is clear that when T10 will mover towards closing for Tie breaker, NO contact in series with the IC 1 trip coil will be energized, and IC 1 breaker will get trip. While before tripping it will sense some time delay to ensure all the 3 breakers are closed in service position only, through 52TS ( test service switch). As cleared in Tie scheme, which will activate time delay relay, which may be preset in desired time. And contact of this time delay relay is provided in series with the tripping circuit of IC -1 breaker. So until unless time period will not be over come, time delays relay contact (62) will remain open. 

Same can be achieved for IC 2, as well Tie breaker it self.