This specification details the minimum technical requirements of high resistance neutral grounding equipment.

The equipment shall be constructed, wired and tested to the following standards:

• Underwriters Laboratories Inc. (UL)
• Standard NMTR, NMTRT
• Institute of Electrical and Electronics Engineers (IEEE)
• Standard 32-1972: Requirements, Terminology, and Test Procedure for Neutral.
• Standard 142-1991: Grounding of Industrial and Commercial Power Systems.
• International Electrical Commission (IEC)
• Standard 529 & 144: Protection Degree for Enclosures
• International Organization for Standardization (ISO)
• Standard 9001:2000: Quality Management Standards and Guidelines

3.0 NEUTRAL GROUNDING RESISTOR

3.1 The neutral grounding resistor will consist of high grade chromium stainless steel or nichrome elements and terminals of high corrosion resistance, double insulated, durable for long years of service, and having extremely high & stable electrical resistivity.

3.2 If more than one frame is required, series connections will be solid copper bus on grid style resistors, teflon wire on wirewound style resistors.

3.3 The resistor frame(s) will be mounted on standoff insulators with a rating equal to or greater than the line-to-neutral voltage.

3.4 The standard temperature rise will be 385°C.

4.0 ENCLOSURE

4.1 Low Voltage Units (600Volts Line-to-Line or below)

a. Assemblies will utilize a wall mounted control enclosure and a separate resistor
enclosure. Customer may elect to upgrade the unit to a free-standing enclosure housing
both the control and resistor components.

b. The control enclosure will be rated NEMA 1. The purchaser may elect to incorporate a
higher NEMA enclosure rating if necessary.

c. The resistor enclosure will be NEMA 1. The purchaser may elect to incorporate a higher
NEMA enclosure rating if necessary.

4.2 High Voltage Units (Above 600 Volts Line-to-Line)

a. Assemblies will utilize a free-standing enclosure housing both the control section and the
high voltage compartment with stepdown transformer.

b. The resistor enclosure will be NEMA 1. The purchaser may elect to incorporate a higher NEMA enclosure rating if necessary.

5.0 CONTROLS

5.1 All control circuitry will operate on 120 Volts a.c.

5.2 All control wiring will be 14 AWG minimum, rated at 600 Volts a.c. Wiring must be sufficiently supported within the enclosure.

5.3 The high resistance neutral grounding equipment will contain the following equipment on an operator's panel on the front of the unit as standard:
a. Line Disconnect Switch
b. Test Push-button
c. A digital display unit containing the following functions:

• Fault Reset Push-button
• Green Light to Indicate "Normal" Operating Status
• Flashing Red Light to Indicate "Fault" Status
• Red Light to Indicate "Harmonic" Status
• Alarm silence push-button
• Pulse on/off push-button
• Amber light to indicate "pulse" status
• Indication of Under-Voltage condition
• Indication of Under-Current condition
• Ethernet/Modbus port for Communications
• Software to Configure and Monitor system remotely
• Software to Data Log / Trend abnormal conditions
• Single Setpoint Meter Relay

5.4 Other equipment is as follows:
a. Alarm Relaying for Local and Remote Annunciation
b. Pulsing Contactor and Timer
c. Grounding Transformer(s) - High Voltage Units Only
d. Copper Grounding Buss - Free Standing Units Only

5.5 The relay to monitor fundamental voltage and current will incorporate an adjustable time delay function to avoid spurious alarms.

5.6 The relay to monitor harmonic voltage and current will incorporate an adjustable time delay function to avoid spurious alarms.

5.7 The optional portable ground detector will be a "split core" type ammeter with a multiple range switch. The clamp must be capable of enveloping a minimum 6" diameter. A short circuiting switch should be provided, along with a carrying case. The handle must be insulated for use on 4,160 volt system.

6.0 MARKINGS

6.1 Wiring is to be numbered consistent with the wiring diagrams. Wire numbers are to be on adhesive labels at each end of the wire.

6.2 Internal control panel components are to be identified with metallized adhesive labels. Text may utilize an abbreviated legend, as long as that legend is identified on the wiring diagram.

6.3 Components on the front control panel are to be permanently identified.

6.4 A list of operating instructions is to appear on the front face of the control panel. These instructions are to cover normal, test, harmonic, and fault conditions.

6.5 Each assembly must include a permanently attached nameplate specifying the following information:

• Manufacturer
• Volts Line-to-Neutral
• Amps
• Ohms
• Seconds
• Extended Time (if applicable)
• Part Number or Drawing Number

7.0 TEST REPORTS & MANUALS

7.1 The high resistance neutral grounding equipment shall be tested as per ANSI/IEEE 32, and other relevant standards.

7.2 Certified test reports are to accompany every unit.

7.3 Complete installation and maintenance manuals shall accompany the shipment of the unit.

8.0 HANDLING

Units must be equipped with removable lifting angles and/or plates for crane hooks or slings, and/or removable base channels for positioning with rollers.

9.0 PREPARATION FOR SHIPMENT

Preparation for shipment must be in accordance with the Seller's standard practices.

Video Tutorial
HIGH RESISTANCE GROUNDING HR103-08

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