Equipment - Resistance Welding Transformers

RoMan Grounding Reactors

RoMan

Grounding Reactors provide protection from electrical shock when direct grounding of the secondary circuit is not practical. They are especially effective on portable guns, and push-pull or series circuits in multi-spot welders.

Available in several sizes and voltage ranges, RoMan grounding reactors can be used with any resistance welding transformer, regardless of make, model, or age.

Purpose: The grounding reactor is used where direct grounding of the welding circuit is not practical to protect the operator from electrical shock hazard, caused by capacitive coupling or insulation failure between primary and secondary coils of the welding transformer.  Typical applications are portable welding gun installations, transgun installations for robots or series welding and push-pull welding circuits in multispot welders.  The AWS publication ANSI/ASC Z49.1-1983 entitled "Safety in Welding and Cutting" lists under paragraph 12.4.6 the grounding reactor as the recommended safety device for these applications.

Rating: The grounding reactor is designed for an operating voltage which be equal to higher than the maximum secondary voltage of the welding transformer and a ground conductor size which must be equal to or larger than required by the National Electric Code.  Series RGR24/4 grounding reactors have an operating voltage of 24 volts maximum at 60 Hertz and a ground conductor size of No. 4 AWG copper wireConstruction and Functions:  The grounding reactor consists of a center tapped coil installed on a magnetic core which is placed in a sheet metal enclosure and fully potted with an epoxy resin.  This construction prevents damage to the insulation from contaminants such as oil, water, weld spatter etc. and protects the device from mechanical damage.Electrically, the lead ends of the grounding reactor coil are connected to the secondary terminals of the welding transformer and the center tap lead is connected to ground.  Under normal conditions the impedance of the grounding reactor limits the flow of ground loop circulating currents but provides a ground path for capacitive charges of the secondary.  In case of an insulation failure between the primary windings and the secondary of the welding transformer, the secondary assumes an electrical potential to ground or in more common terms, becomes electrically "live".  The resultant current flows in both parts of the center tapped coil which "buck" each other creating a low impedance path to ground and causing the primary protection device to open.Application:  Select the appropriate grounding reactor by:

  1. Determine the maximum secondary voltage of the welding transformer to be protected.  See Column 1 of Selection GuideDetermine the ampere rating of the fuse or circuit breaker installed in the primary circuit to protect the welding transformer.  See Column 2 of Selection Guide.Select type of connection desired.  See Column 3 of Selection Guide.
  2. Select grounding reactor model number.  See Column 4 of Selection Guide.

Selection Guide

Column 1 Maximum Secondary Voltage Column 2 Fuse Ampere Rating

       Column 3 Type of Connections

Column 4 Grounding Reactor Model Number

Approx. KVA Rating at 50% Duty Cycle

240 V 480V

Required Ground Conductor Size

Weight (LBS)

Drawing No.
Up to 24 Volts/ 60 Hz Up to  300 Amp
#4 AWG Leads
Solderless Lugs
RGR 24/4-1099
RGR 24/4-1100
75 150
75 150
#4 AWG CU
#4 AWG CU
18
16
R1474
R1473
Up to 28 Volts/ 60 Hz Up to  300 Amp
#4 AWG Leads
Solderless Lugs
RGR 28/4-1150
RGR 28/4-1151
75 150
75 150
#4 AWG CU
#4 AWG CU
20
18
R1474
R1473
Up to 28 Volts/ 60 Hz Up to  500 Amp
#2 AWG Leads
Solderless Lugs
RGR 28/2-1152
RGR 28/2-1153
150 300
150 300
#2 AWG CU
#2 AWG CU
27
24
R1474
R1473
Up to 34 Volts/ 60 Hz Up to  500 Amp
#2 AWG Leads
Solderless Lugs
RGR 34/2-1513
RGR 34/2-1514
150 300
150 300
#2 AWG CU
#2 AWG CU
31
28
R1474
R1473

Spotwelding Consultants Inc.

4209 Industrial
Rowlett, Texas 75088
Toll Free: 888-255-6780
Phone: 972-475-0874
Fax: 972-475-5024