Primary injection testing is used to verify how an electrical protection system performs when current is injected through the primary circuit.

Unlike secondary injection testing, which mainly checks the relay or secondary-side logic, primary injection testing exercises more of the complete protection chain. Depending on the setup, it can include the current transformer primary circuit, secondary wiring, protective relay, trip circuit, alarm circuit, breaker operation and associated control wiring.

The SMC Raptor is a modular primary injection test system designed for medium- and high-voltage commissioning and maintenance work. It can support primary current injection, relay testing, current-transformer testing, recloser testing, switchgear testing, heat runs and ground-grid testing.

For Canadian utilities, electrical contractors, industrial facilities, mines, power plants, renewable-energy sites and commissioning teams, the Raptor is useful when high current must be applied in a controlled, portable and repeatable way.

What Is Primary Injection Testing?

Primary injection testing applies current through the primary side of the electrical system.

The goal is to verify that the protection scheme responds correctly under simulated fault or load conditions.

A primary injection test may help confirm:

• CT ratio
• CT polarity
• CT burden
• Secondary wiring condition
• Relay operation
• Breaker trip performance
• Alarm and trip circuits
• Recloser operation
• Switchgear protective functions
• End-to-end protection performance

Secondary injection testing is still important, but it does not prove the full installation. The original JM Test article correctly notes that primary injection is often performed after secondary injection testing because it checks more of the complete protection path.

This does not mean every job always requires primary injection. The required test depends on the commissioning plan, maintenance standard, equipment type, owner specification and risk assessment.

What Is the SMC Raptor?

The SMC Raptor is a modular primary injection system made up of a master unit and optional slave units.

The simplest configuration includes a master unit, control interface, measurement inputs, voltage and current test sources, binary input and a 3 kVA digital amplifier in a portable 35 kg body. SMC states that this basic configuration can provide up to 9,500 A current injection with variable frequency.

The system uses a pass-through current-generation method. Instead of connecting output terminals in the traditional way, the current conductor passes through the centre opening of the Raptor unit and connects to the device being tested. Multiple passes or parallel cables can be used to increase effective output capability, depending on the test setup.

For higher-power applications, slave units can be added. SMC lists configurations from C-05 through C-45, with the C-35 using one master and three slave units, and the C-45 using one master and four slave units.

Main Raptor Configurations

The original JM Test article mentions C-05, C-15, C-25 and C-35 rental configurations. SMC’s current product page also lists a C-45 configuration, so the Canadian article should not imply that C-35 is necessarily the highest available Raptor configuration unless JM Test Canada confirms its rental fleet.

Key Features of the SMC Raptor

Modular Design

The Raptor can be configured with only the units needed for the job.

This matters because high-current testing often involves heavy equipment, long cables and difficult site conditions. A modular system allows the team to bring more power when needed and avoid carrying additional units when the job is smaller. SMC describes the system as expandable and designed to avoid unnecessary equipment on site.

Pass-Through Current Injection

The Raptor’s pass-through technique lets the test conductor pass through the centre of the unit.

This design can reduce intermediate connections and help place the test set closer to the equipment under test, which can reduce cable length and losses.

Automatic Output Regulation

The Raptor is a stabilized injection system. It compensates for small supply and load variations to maintain the test value during the job.

This is useful during trip-time tests, breaker tests and other applications where a stable injected current is needed.

Variable Frequency Output

The Raptor can work at different frequencies. SMC lists operation from 20 to 400 Hz for the high-current output in the C-05 configuration description.

Variable frequency can help reduce interference from the network fundamental frequency and support certain diagnostic applications.

Handheld Control Interface

The Raptor handheld control unit allows the operator to control and monitor the test process.

JM Test’s source article describes the handheld interface as having a TFT display, touch panel, stylus, wheel/click encoder and test templates for common tests.

Built-In Test Templates

The Raptor includes pre-configured test templates for common applications.

JM Test lists templates such as overcurrent, MCB/MCCB, CT ratio/phase/burden, VT burden/phase, CT magnetization curve, AC resistance, knee point and recloser testing.

Templates can save time, but they do not replace a qualified test plan. The technician still needs to confirm the test method, current level, trip criteria, wiring, PPE and equipment limitations.

Results Storage and Reporting

SMC states that custom settings and test results can be stored and downloaded through a USB connection, and the product page lists test and result storage, download and reporting among the system characteristics.

This can help with commissioning records, maintenance documentation and customer handover packages.

What Can the Raptor Be Used For?

Primary Current Injection Testing

Primary current injection testing is one of the Raptor’s core applications.

It can be used to inject current into the primary circuit and verify the protection scheme under controlled conditions. This may include CTs, secondary wiring, protective relays, trip circuits, alarm circuits and circuit breakers.

Primary injection is especially useful during:

• New substation commissioning
• Switchgear commissioning
• Protection-system modifications
• CT replacement
• Relay upgrades
• Breaker maintenance
• Troubleshooting unexpected trips
• End-to-end protection verification

Relay Testing

The Raptor can simulate primary faults to check whether protective relays operate correctly.

The source material notes that trip times can be measured and registered by the system.

This is different from secondary relay testing. Secondary injection proves the relay inputs and logic. Primary injection helps prove more of the installed protection system.

Circuit Breaker Testing

The Raptor can support circuit-breaker trip testing and operating-time analysis.

Applications may include:

• Low-voltage breaker trip testing
• Thermal trip testing
• Magnetic trip testing
• Air circuit breaker testing
• MCB and MCCB testing
• Breaker timing checks
• Trip circuit verification

JM Test lists thermo-magnetic circuit breaker, MCB/MCCB and overcurrent relay templates among the built-in options.

The correct current level and test duration must come from the breaker manufacturer, maintenance standard or project procedure.

Current Transformer Testing

The Raptor can support CT-related tests such as:

• CT ratio
• CT phase angle
• CT polarity
• CT burden
• CT magnetization curve
• Knee-point-related testing
• Rogowski or low-power CT testing

The original article lists CT ratio/phase/burden, CT Rogowski, CT magnetization curve and knee point among the available templates.

For Canadian utility and industrial sites, CT testing is important because incorrect ratio, polarity or wiring can cause protection misoperation, inaccurate metering or failed commissioning checks.

Recloser and Sectionalizer Testing

The Raptor can be used for recloser and sectionalizer testing by simulating high-current fault conditions.

SMC’s product literature describes testing recloser opening and reclosing times, number of operations and total clearing time under simulated fault conditions. It also describes sectionalizer lockout testing by pulsing current to simulate upstream recloser operation.

This can be useful for distribution utilities and contractors working on overhead or pad-mounted distribution protection.

Switchgear Testing

Switchgear testing can include high-current testing of low-voltage switchgear, short-time current withstand checks and breaker trip performance.

SMC lists switchgear testing and MCB/MCCB/ACB trip-time performance among the Raptor applications.

The test setup should account for switchgear rating, bus arrangement, breaker type, available test current, cooling time and manufacturer limits.

Heat Runs

The Raptor can maintain stable current for heat-run applications.

SMC identifies heat runs as one of the applications supported by the amplifier-based high-current generation system.

Heat-run testing should be carefully controlled because conductor temperature, connection condition, enclosure ventilation and test duration all affect the result.

Ground Grid Testing

The Raptor can also support ground-grid-related testing.

SMC lists ground-grid testing among the Raptor applications, and the Raptor HV accessory can support step-and-touch voltage measurement applications.

Ground-grid testing should not be treated as the same thing as a simple continuity check. The correct method depends on the site, soil conditions, grid design, available test paths and applicable engineering requirements.

Transformer-Related Testing

The Raptor can support current-transformer and voltage-transformer testing, as well as some power-transformer-related applications.

SMC states that adding the Raptor HV accessory can enable AC voltage tests up to 2,000 V, including transformer evaluation, voltage withstand/isolation tests and step-and-touch voltage measurement.

Use this carefully in the Canadian article. The Raptor is not a universal replacement for every dedicated transformer test set. It can support certain transformer-related tests when configured correctly.

Primary Injection vs Secondary Injection

Secondary Injection

Secondary injection applies test signals directly to the relay or protection device secondary inputs.

It is used to check:

• Relay settings
• Trip curves
• Logic
• Digital inputs and outputs
• Protection functions
• Communication-based functions
• Trip outputs

Secondary injection is usually easier, faster and lower energy than primary injection.

Primary Injection

Primary injection applies current through the primary current path.

It helps check:

• CT primary circuit
• CT ratio and polarity
• Secondary wiring
• Relay response
• Breaker trip circuit
• Breaker operation
• Complete protection scheme

JM Test’s original article explains that secondary injection does not check all components in the protection system and that primary injection better mimics installed operating conditions.

The practical rule is not “one is better than the other.” Both are useful. Secondary injection is usually used to prove the relay and logic. Primary injection is used when the installed protection chain must be verified more completely.

Why Compliance Voltage and Cable Setup Matter

High current alone is not enough.

To drive current through the test object, the test set must overcome the impedance of:

• Test cables
• Cable length
• Cable cross-section
• Busbars
• Breaker contacts
• CT primary path
• Connections
• Clamps
• The device under test

This is why Raptor configurations with more slave units provide more power and compliance voltage. SMC explains that higher configurations are used where high current values require more power to reach the desired current, especially when longer cables or more demanding loads are involved.

A low-power configuration may be suitable when the test set is close to the load. A higher-power configuration may be required when the test object is farther away or the circuit impedance is higher.

Safety Considerations for Canadian Worksites

Primary injection testing is high-energy electrical work.

It may involve:

• High current
• Energized or recently de-energized equipment
• Stored energy
• Induced voltage
• Trip circuits
• Moving breaker mechanisms
• CT secondary hazards
• Temporary cables
• Large clamps
• Grounding and bonding concerns
• Arc-flash and shock exposure

Canadian teams should follow the employer’s electrical safety programme, applicable federal/provincial/territorial requirements, manufacturer instructions and site-specific procedures.

CSA Z462:24 provides requirements and guidance for electrical safety management systems, safe work procedures, PPE selection and identification/training of qualified electrical workers exposed to hazards associated with energized electrical equipment. It is intended for use with the Canadian Electrical Code, CSA Z460 and relevant Canadian safety regulations.

Important controls include:

• Approved test plan
• Job briefing
• Qualified workers only
• Lockout and isolation where required
• Verified absence of voltage where required
• Shock and arc-flash risk assessment
• Correct PPE
• Barricades and controlled access
• Properly rated cables and clamps
• Secure temporary connections
• CT secondary safety controls
• Clear trip and reset procedure
• Communication between test operator and field personnel
• Post-test restoration checks

This article is educational content, not a substitute for a site-approved primary injection test procedure.

When to Use the Raptor Instead of Traditional High-Current Test Sets

Traditional variac-based primary injection sets can be large, heavy and difficult to move.

The Raptor is designed to be more portable and modular. The master unit is listed at 35 kg, and additional power can be added using slave units.

The Raptor is useful when the team needs:

• Portable high-current injection
• Modular power expansion
• Stable current regulation
• Variable-frequency output
• Built-in templates
• Results storage
• More flexible cable setup
• Substation or field mobility
• Multiple test applications from one system

It may not be the best choice for every job. Some tests may require another current level, another duty cycle, different voltage capability, specialized timing tools or a dedicated transformer/breaker test system.

What to Confirm Before Renting or Buying

Before selecting a Raptor configuration, confirm:

• Required test current
• Required compliance voltage
• Test duration
• Distance from test set to test object
• Cable size and length
• Available site power
• Breaker or CT type
• Trip-time measurement requirements
• Binary input requirements
• Need for HV accessory
• Need for polarity tester
• Required reports or data export
• Site access and transport limits
• Outdoor or indoor conditions
• Canadian availability of the exact configuration

The original US article states that JM Test rents C-05, C-15, C-25 and C-35 configurations with slave units. For the Canadian page, this claim should be checked with JM Test Canada before publishing because rental inventory may differ by country.

Practical Takeaway

The SMC Raptor is a modular primary injection test system for substation, switchgear and protection-system testing.

It can support:

• Primary current injection
• Relay testing
• Circuit-breaker testing
• CT ratio, phase, burden and polarity checks
• Recloser and sectionalizer testing
• Switchgear testing
• Heat runs
• Ground-grid-related testing
• Selected transformer and high-voltage applications with accessories

Its main advantages are modular power, portability, pass-through current injection, automatic output regulation, variable-frequency capability, built-in templates and result storage. SMC lists configurations from the 3 kVA C-05 master configuration up to higher-power master-plus-slave configurations, including C-35 and C-45.

For Canadian commissioning and maintenance teams, the correct Raptor configuration should be selected based on current level, compliance voltage, test distance, cable setup, test duration, reporting requirements and site safety procedure.

JM Test Systems Canada can support electrical teams with primary injection test equipment, high-current test sets, electrical safety equipment, rentals and calibration services. Confirm exact model availability, accessories and rental configuration before publishing a firm service claim.