Auto Coordination Options

Auto Coordination Options enable you to specify how your system will be coordinated. To select the auto coordination options:

  • In the Coordination focus, click PDC Options and then select the Auto Coordination tab.
  • In the Coordination or TCC focus, click the arrow below SmartPDC and select Smart PDC Options.

General

Figure 1: Coordination Options - General

Option Description

How do you want to handle protective devices with no data?

Enables you to decide how to proceed when a protective device to be coordinate does not contain trip data. The choices are:

  • Automatically Skip Device: Skips the device with incomplete data and proceeds with other devices. The protective device is not used in coordination. The auto-coordination process reports incomplete data for protective device without data.
  • Cancel Auto-Coordination Run: Stops the entire Auto-Coordination process.
  • Prompt to Skip or Cancel: Enables you to decide one of the above two methods during the auto coordination process by providing a message.

Default Insufficient Data Handling

The trip settings are set as selected below, if the curve cannot be coordinated with other equipment because of insufficient data.

Set LTPU to: Select the type of load current calculation to use to set LTPU. The following choices are available:

  • Connected Amps: Amp value for the total kVA of all downstream loads.
  • Demand Amps: Amp value for the total (kVA * Demand Factor) of all downstream loads.
  • Code Factor Amps: Amp value calculated using appropriate code factors and demand factors, following a Code (such as NEC).
  • Design Amps: Amp value calculated using appropriate code factors and diversity factor and Design multiplier.

If zero, then: If the selected load type amps are equal to zero, the LTPU is set as selected. The possible LTPU selections for this case are Min, Medium, and Max.

Set STPU to: Select the setting for STPU if coordinating equipment does not have sufficient data or coordinating equipment is not present. The possible STPU selections are Min, Medium, and Max.

Set INST to: Select the setting for INST if coordinating equipment do not have sufficient data or no coordinating equipment is present. The possible STPU selections are Min, Medium, and Max.

Curve comparison precision

Select the amount of precision used while coordinating between curves. Selecting a higher level of precision will enhance coordination. There are three levels of precision are shown below. The default level of precision is Normal (fastest).

  • Normal (fastest)
  • High
  • Aggressive (slowest)

The selected level of precision will affect the amount of time needed for EasyPower to auto coordinate each selected protective device.

Auto-coordination analysis

Select the analysis:

  • Phase Only: Auto coordination only coordinates phase settings.
  • Ground Only: Auto coordination only coordinates ground settings.
  • Both Phase and Ground: Auto coordination coordinates phase settings and ground settings at the same time.

Include 87% transformer shift during coordination

The program will take into consideration the 87% factor while comparing primary currents with secondary in a wye-delta transformer with line-to-line fault on the delta side.

Generate report only without changing database

This enables you to view comments regarding auto coordination of equipment, without changing protective device settings in the temporary database. When the check box is not selected, the settings are changed temporarily in Coordination focus. These changes need to be stored to the database when returning to Database Edit focus if you want to save them.

Verify that Thermal Magnetic Trip and Fuse amps protect equipment

If this check box is selected, the program compares the trip amps of the breaker or fuse with the rated amps of the protected cable or transformer, and reports possible overload protection issues.

Transformer

Figure 2: Auto Coordination Options - Transformer

Option Description

NEC Requirements for Transformer Protection

The table is the NEC Table 450-3(A) for transformer primary over 600V. The table shows the maximum rating or setting of over current protection for transformers. You can change the values in the spreadsheet.

With SSTs, apply transformer FLA NEC limits using

When setting SST for transformer FLA, the LTPU is set based on the following selections:

  • LTPU setting amps: LTPU setting is set based on LTPU amps.
  • LTPU min tolerance amps: LTPU setting is set based on LTPU minimum clearing curve amps.

Allow one setting past transformer FLA NEC limit for LTPU selection

Selecting the check box increases LTPU setting by one past the selected transformer FLA NEC limit. If the check box is not selected, LTPU is set as originally specified.

How should the LTPU selection of LV devices be prioritized?

LTPU coordination is selected by coordinating with other protective devices or with maximum transformer FLA.

  • Use closer selectivity with downstream protective devices: LTPU setting is set based on coordination with downstream protective devices.
  • Use Max transformer Amps: LTPU is set based on maximum transformer amps.

Minimum gap between inrush and relay

Sets the relay time delay at specified seconds higher than the transformer inrush time.

Line

Figure 3: Auto Coordination Options- Line

Option Description

For LV devices, set line ampacity protection using

Select the cable protection method from the following:

  • LTPU settings amps: Adjusts LTPU settings of solid state trip such that the LTPU nominal amps are lower than the downstream cable.
  • LTPU min tolerance amps: Adjusts LTPU settings of solid state trip such that the LTPU minimum tolerance amps are lower than the downstream cable.

Allow one setting past line ampacity limit for LTPU selection

When the check box is selected, LTPU setting is set to the next setting past the cable ampacity. As per NEC, this is enabled only when the amp rating is 800A or less.

How should the LTPU selection of LV devices be prioritized?

Enables you to select the method for coordinating solid state trip and cable.

  • Use closer selectivity with downstream protective devices: The solid state trip device coordinates with downstream protective devices.
  • Use line ampacity: The cable ampacity is used to set the LTPU setting amps, without comparing with downstream protective devices.

Tolerance allowed before showing underutilized warning

If the trip amps of the device is lower than the cable ampacity by the specify tolerance, the report indicates that the cable is underutilized.

Load

Figure 4: Coordination Options - Load

These options control how coordination is handled for single loads.

Option Description

Set LTPU to

Select the type of load current calculation to use to set LTPU. The following choices are available:

  • 100% Connected Amps: Amp value for 100% of kVA load.
  • Scaled Connected Amps: Amp value for the scaled kVA of load.
  • Demand Amps: Amp value for the total (kVA * Demand Factor) of load.
  • Code Factor Amps: Amp value calculated using appropriate code factors and demand factors, following a Code (such as NEC).
  • Design Amps: Amp value calculated using appropriate code factors and diversity factor and Design multiplier.

Set STPU to

Select one of the following STPU settings when coordinating with a single load: Min, Medium, or Max.

Set INST to

Select one of the following INST settings when coordinating with a single load: Min, Medium, or Max.

Capacitor

Figure 5: Auto Coordination Options - Capacitor

Option Description

Minimum gap between inrush and relay

Set the minimum time gap in seconds between a capacitor’s inrush with a relay to ensure selective coordination. The range is from 0.01 to 10 seconds.

Motor

Figure 6: Auto Coordination Options - Motor

Use to set tolerances when comparing trip curves.

Option Description

FLA

Trip curve will be set outside tolerance boundary when comparing with Motor FLA. The range is –50 % to 50 %.

LRA

Trip curve will be set outside tolerance boundary when comparing with Motor Locked Rotor Amps (LRA). The range is –50 % to 50 %.

Asym

Trip curve settings will be set outside tolerance boundary when comparing with Motor Asymmetrical inrush amps. The range is –50 % to 50 %.

Damage I2T

Sets the minimum gap between the protective device trip curve and the thermal I^2T damage curve of the motor. The range is –50 % to 50 %.

Note: When coordinating protective devices at low voltage, EasyPower assumes the maximum downstream motor size to be 250 HP.

Fuse

Figure 7: Auto Coordination Options – Fuse

Option Description

Average Melting tolerance

Used only if the fuse curves are average melting curves. Tolerance enables program to set boundary for fuse curve coordination. The tolerance range is from –50 to 50.

Relay

Figure 8: Auto Coordination Options – Relay

Option Description

HV Relay tap default

When a relay has only cables as downstream equipment, the Tap is set to the specified value times the ampacity of cable.

HV Time Dial with no dependencies

When a relay does not have dependencies, its time dial is set such that the relay trips close to the specified time at the maximum short circuit current available at the CT for the relay. You can also have the time dial set at the specified value instead of basing it on the short circuit current.

HV Instantaneous with no dependencies

The instantaneous is set to the specified multiple of maximum short circuit current.

Minimum Gap Tolerance

The desired minimum time difference between two relays is the sum of Over Travel time, Safety Margin, Auxiliary relay time, and circuit breaker opening time. The time dial settings available in a relay may not provide the exact desired minimum time difference. This Minimum Gap Tolerance enables you to set the time delay of the relay up to the specified percentage higher than the desired minimum time. For example, the desired time difference between two relays is 0.283 seconds. If the Minimum Gap Tolerance is 20%, the program lets the upstream relay time dial to be set such that the time difference is not greater than 0.33 seconds (0.283 + 20%).

Inst Safety Margin

This is the factor used in setting instantaneous pickup. A factor of 1.1 corresponds to a 10% tolerance. For example, if the downstream relay has instantaneous pickup of 3000 Amps, then the upstream relay pickup needs to be higher than 3300 Amps (3000*1.1).

Instantaneous Selection Base on Transformer Short Circuit Let-Through Current With DC Offset Filter

Solid state relays typically have dc offset filters so that trip characteristics are based only on the AC component of currents. The relay library has data indicating whether the relay has a dc offset filter. The DC component may not be completely filtered.

Use Calculated SC Asym Offset

When this check box is selected, the programs uses the asymmetrical currents (with dc component) it calculates. If the check box is not selected, the offset specified in the field below is used.

Assume- Asym Mult

If the Use Calculated SC Asym Offset check box is selected, then the specified value will not be used.

Without DC Offset Filter

Relays that do not have dc offset filters, respond to the asymmetrical current.

Relay Minimum Time Gaps

Figure 9: Auto Coordination Options – Relay Minimum Time Gap

Option Description

Relay Minimum Time Gaps

The time gap between two protective devices is to ensure selective coordination. It is dependent on the combination of devices. The spreadsheet lists different combination of protective devices consisting of induction disk (ID) and solid state (SS) relays, fuses and LV breakers. The minimum time gap is sum of the Overtravel, Safety Margin, auxiliary and breaker opening time.

 

Reports

Figure 10: Auto Coordination Options – Reports

More Information

Auto-Coordination  
Auto Coordination Process  
Protective Devices that can be Auto Coordinated  
Auto Coordination Report