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I-Gard SIGMA 3 Manual

Ground fault & monitoring relay
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SIGMA 3
C-EG44EM, Manual Rev 1. May 2023

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Summary of Contents for I-Gard SIGMA 3

  • Page 1 SIGMA 3 C-EG44EM, Manual Rev 1. May 2023...
  • Page 2 ABOUT I-GARD I-Gard’s commitment to electrical safety provides both industrial and commercial customers with the products needed to protect their electrical equipment and the people that operate them. As the only electrical-safety focused company whose product portfolio includes neutral grounding resistors, high-resistance grounding systems and optical arc mitigation, we take pride in our technologies that reduce the frequency and impact of electrical hazards, such as arc flash and ground faults.

  • Page 3: Table Of Contents

    4. Trip Relay and Auxiliary Fault Relays ........................7 5. LED Indicators and Diagnostics ..........................7 6. Settings ................................... 9 7. Use with SIGMA 3-TDM Touchscreen Display Module ..................17 8. MODBUS Communication ............................21 9. Installation ................................... 26 10. Commissioning ................................29 11.
  • Page 4 FIGURES Figure 10.12: Conductance vs Resistance - HF1, Open and Short Circuit Figure 10.13: SIGMA 3- Status Screen Figure 10.14: SIGMA 3 System Calibration Screen (NGR FLT) Figure 12.1: SIGMA 3 Dimensional Drawings Figure 12.2: SIGMA 3- TDM Dimensional Drawings...

  • Page 5: Introduction

    CSA C22.1 section 10-302. The SIGMA 3 monitor relay provides a current source output for connection to a 1mA full scale ammeter. The output signal is proportional to the measured current and is expressed as a percentage of the NGR let-through current setting.
  • Page 6 See Figure 3.1 below for the typical system with the SIGMA 3 connections. Figure 3.1: SIGMA 3 Typical System Diagram (HRG System)
  • Page 7 The SIGMA 3’s NGR let-through current setting is set by DIP switch to match the rating of the NGR. The trip level is DIP switch selectable as a percentage of the NGR let-through current setting and can be set as: 5%, 10%, 15%, 20%, 25%, 30%, 40%, and 50%.
  • Page 8 3.3 NGR Monitoring The SIGMA 3 monitor relay also monitors the health of the NGR to identify an open or short circuit condition. If the SIGMA 3 determines that the NGR is not healthy the NGR FLT LED illuminates, the NGR FLT form-C contact energizes, and the trip relays energize.

  • Page 9: Trip Relay And Auxiliary Fault Relays

    All relays are electrically held, i.e. when control power is off, the relays are always in the de-energized state. The de-energized states are shown on the front of the SIGMA 3. Note that this is irrespective of the trip relay operating mode. All relays can be in one of two states: idle or tripped.
  • Page 10 The Red GND FAULT LED will turn ON when the SIGMA 3 has detected and qualified a ground fault. The Red GND FAULT LED will remain ON until the SIGMA 3 is manually reset even if the ground fault condition has been rectified.

  • Page 11: Settings

    6.1 Trip Relay Operating Modes The trip relay operating settings can be set with DIP switch 1. The SIGMA 3 can be set for a shunt trip operating mode (not fail- safe) or an undervoltage trip operating mode (fail-safe) operation with the trip relay operating mode dip switch. See Table 6.1 for configuration details.
  • Page 12 TRIP MEMORY Setting, restore the state of the trip relay when control power is applied. The SIGMA 3 can be set for trip memory ON (DIP switch #2 UP) or trip memory OFF (DIP switch #2 DOWN). See Table 6.2 for configuration details.

  • Page 13: Dip Switch Setting

    5 Amperes through 400 Amperes using a standard I-Gard TxA ZSCS. The NGR let-through current settings in Table 6.6 are intended to show that the SIGMA 3 monitor relay can be configured for let-through currents ranging from 1 Ampere through 4 Amperes using a standard I-Gard TxA ZSCS with the conductor carry- ing the NGR current wrapped through the CT’s primary window 10 times to create a primary winding of 10 turns.

  • Page 14: Dip Switch Settings

    DIP SWITCH #2 - TRIP MEMORY SELECTION (left hand array) Trip Memory On/Off Dip Switch Settings TRIP MEMORY ON Control voltage off after trip: When control voltage restored Trip and Aux relays idle* then immediately re-trip (within 2 seconds). TRIP MEMORY OFF Control voltage off after trip: When control voltage restored DOWN...
  • Page 15 (U = Up, D = Down) 1350 1450 1550 1650 1750 1850 1950 2050 2150 2250 2350 2450 2550 2650 2750 2850 2950 3050 3150 Table 6.3: Ground Fault Trip Time Delay Settings Dip Switches #3-#4-#5-#6-#7 (left hand array) DIP SWITCH #8,9,10 - GROUND FAULT TRIP LEVEL % (left hand array) (U = Up, D = Down) Ground Fault Trip Level (% of NGR Dip Switch Settings...
  • Page 16 DIP SWITCH #11 - SYSTEM FREQUENCY SELECTION (right hand array) System Frequency 50/60 Hz Dip Switch Setting System Frequency 50 Hz System Frequency 60 Hz DOWN Table 6.5: System Frequency Selection Dip Switch #11 (right hand array) DIP SWITCH # 12, 13, 14, 15, 16- NGR let-through current (right hand array) (U = Up, D = Down) NGR Let-Through Dip Switch Settings...
  • Page 17 (U = Up, D = Down) TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA TxA or Rx-yA...
  • Page 18 C: Continuous Duty The user is about to configure SIGMA 3 DIP switches according to the particular system; the user is planning to set up fail-safe operating mode, he decides to turn on the Trip Memory toggle, Ground Fault Trip Time Delay will be set at 3150 milliseconds, 5% Ground Fault Trip Level will be set up at 5% (of the NGR let-through current (5% of 5 Amps for this particular example) and frequency system is 60 Hz.

  • Page 19: Use With Sigma 3-Tdm Touchscreen Display Module

    7. USE WITH SIGMA 3-TDM TOUCHSCREEN DISPLAY MODULE The SIGMA 3 can be used with a touchscreen HMI called the SIGMA 3-TDM. The SIGMA 3 is connected to the SIGMA 3-TDM using its MODBUS communication port. The connection of the SIGMA 3 to the SIGMA 3-TDM is shown in Figure 7.1.
  • Page 20 Figure 7.2: Home Screen Figure 7.3: Status Screen Figure 7.4: Event Log Screen...
  • Page 21 Figure 7.5: Settings Screen Figure 7.6: SIGMA 3 and Alarm Settings Screen Figure 7.7: Pulse Contactor Settings Screen...
  • Page 22 Figure 7.8: Communications Settings Screen...

  • Page 23: Modbus Communication

    The shield of the cable between nodes should not be continuously grounded but should be grounded at one end. The cable may be grounded at the SIGMA 3 using the ground connection provided on terminal # 6. Figure 8.1 (a):...
  • Page 24 This document summarizes the format and function of these registers. The request from the master is always 8 bytes long and are as shown in the table below. In the MODBUS RTU system the SIGMA 3 operates in a client/server communica- tions model or master/slave communications model.

  • Page 25: Starting Address

    There are times when the SIGMA 3 relay processor will not be able to respond to a request since it is busy with other tasks and no response will be returned. For this reason it is recommended to request the maximum number of registers used by the...
  • Page 26 Low Peak Limitation 0-0xFFFF – (0-65535) 40039 nnnnH High Peak 0-0xFFFF – (0-65535) Limitation 40040 nnnnH Coupling 0-0xFFFF – (0-65535) Impedance 40041 nnnnH Value Fluctuating - 0-0xFFFF – (0-65535) 40042 nnnnH Value Fluctuating - 0-0xFFFF – (0-65535) High Table 8.4: SIGMA 3 Relay Register Definitions...
  • Page 27 325 A 0x1D 350 A 0x1E 375 A 0x1F 400 A Table 8.6 Table 8.5: SIGMA 3 System Voltage Table 8.6: SIGMA 3 Current Table 8.7: SIGMA 3 Ground Fault Trip Level (%) Table 8.8: SIGMA 3 Pulsing Frequency table...

  • Page 28: Installation

    SIGMA3-TDM functionality. 9.1.2 Mounting Mount the SIGMA 3 monitor relay horizontally using 35 mm DIN rail bolted or firmly fixed to flat surface. Allow at least 20 mm of rail to extend beyond each end of the relay.
  • Page 29 Refer to Figure 3.1 or 3.2. The R terminal of the NGRXS sensing resis- tor must be connected to the appropriate terminal of the SIGMA 3 monitor relay as shown in Figure 3.1 or 3.2. The G terminal of the NGRXS sensing resistor should be connected to a suitable ground point.
  • Page 30 Important: Neutral is bonded to ground ONLY through the resistor (NGR) 2.- Sensing Resistors: NGRX to Terminal # 38 - SIGMA 3 HF1 NGRS - Terminal # 45(R) and #46 (G) to SIGMA 3 Terminal #45 and #46 **Important: These terminals are Polarity Sensitive 3.- TxA Zero Sequence Current Sensors:...

  • Page 31: Commissioning

    Figure 9.1: SIGMA 3 Terminal Connections 10. COMMISSIONING A general breakdown of commissioning of the SIGMA 3 would involve the following: Review of installation and condition of unit Verification of connections Verification of settings Energization of SIGMA 3 Functional Verifications:...
  • Page 32 10.1 NGR Monitoring - Calibration Procedure The SIGMA 3 relay utilizes three methods to determine if the NGR path is within the required short/open circuit parameters - 1) Measurement Mode Measurement mode continuously monitors the current through the Zero Sequence Current Sensor (ZSCS) and the voltage across the NGR to monitor the condition of the expected impedance between N and G.
  • Page 33 When there is no voltage or current being measured by the system (less than 5%), the integrity of the resistor can no longer be monitored by using the method described in 1). To accommodate for this scenario, the SIGMA 3 relay actively applies a High Frequency current (HF) through the NGRXS to the resistor to confirm that the resistor is still connected from neutral to ground.
  • Page 34 Calibration Procedure using the SIGMA 3-TDM 1. Ensure the SIGMA 3-TDM is connected to the SIGMA 3 as shown in Figure 10.4 below, or refer to the installation section C-EG44-EM Figure 10.4: SIGMA 3 -TDM to SIGMA 3 connection 2. From the home page, select "Admin" and enter password (default password is 8421), and press "Enter".
  • Page 35 SIGMA 3 & Alarm Settings Screen 5. Enter SIGMA 3 ID - this must correspond to the last three digits of the SIGMA 3 serial number (found on the right side of the SIGMA 3 relay). Then check on “Active” box.
  • Page 36 Figure 10.8: SIGMA 3 Home Screen - Admin Mode Figure 10.9: SIGMA 3 Home Screen - Reset tab 9. Select "Settings" and enter the "SYSTEM CALIBRATION" screen.
  • Page 37 Figure 10.10: SIGMA 3 Settings Screen - System Calibration tab 10. Turn "Calibration Mode" ON. Confirm your SIGMA 3 ID is correct and the GREEN pilot light is visible. Figure 10.11: SIGMA 3 System Calibration Screen...
  • Page 38 11. The “System Calibration” screen provides the following: a. Given Parameters: i. Conductance Measurement ii. Online Coupling Impedance iii. Low Fluctuating Value iv. High Fluctuating Value b. User Inputs: i. Open Circuit Threshold ii. Short Circuit Threshold iii. Low Peak Threshold iv.

  • Page 39: Figure 10.12: Conductance Vs Resistance - Hf1, Open And Short Circuit

    *This is typically enough to finalize calibration. In some cases, there may exist a voltage across the NGR but lacks enough current to trigger measurement mode. This is evident by i) high “Fluctuating Values”, and ii) Neutral-Ground Voltage with minimal cur- rent, as seen below: Figure 10.13: SIGMA 3 Status Screen...

  • Page 40: Figure 10.14: Sigma 3 System Calibration Screen (Ngr Flt)

    Figure 10.14: SIGMA 3 System Calibration Screen (NGR FLT) *If an NGR FLT is still seen, continue: 14. The following formula must be fulfilled: Online Coupling Impedance > [(V + Zero Drift) / 255] THEORETICAL Where V can be identified from the following table:...
  • Page 41 10.2 Warning Concerning Hi-Pot and Dielectric Testing of the System As the SIGMA 3 monitor relay, NGRXS sensing resistor and ZSCS have undergone and passed high-pot testing at the factory, field testing of the relay is unnecessary and may damage these components. For any high-pot tests or dielectric withstand tests on the system conducted in the field, the SIGMA monitor relay, NGRXS sensing resistor and ZSCS must be prepared as described below to avoid damaging this equipment.

  • Page 42: Technical Specifications

    10 A@240 VAC, 8A@24 VDC, 1/2 HP@240 VAC Type: 1 Form C (NO/NC) Pulsing NGR Fault Relay: Output: Max: 1 A @ 12 VDC SIGMA 3 Health Type: 1 Form A (NO), Fail-safe Mode Monitoring Relay Rating: 1 A @ 120 VDC...

  • Page 43: Dimensional Drawings

    12. DIMENSIONAL DRAWINGS Figure 12.1: SIGMA 3 Dimensional Drawings Figure 12.2: SIGMA 3-TDM Dimensional Drawings...

  • Page 44: Part Numbers

    SIGMA 3-TDM Mounting Details Recommended height to install the SIGMA 3-TDM (Display Module) is between 3 to 5 feet (1-1.5 meters) from the floor to the center of the SIGMA 3-TDM Display which will allow the user to comfortably set up system parameters, to conduct calibration procedure and to take advantage of the SIGMA3-TDM functionality.
  • Page 45 Designed & Manufactured C-EG44EM REV.1 SIGMA 3 MANUAL in Canada Phone: 905-673-1553 Fax: 905-673-8472 Toll Free: 1-888-737-4787 support@i-gard.com www.i-gard.com...

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