TEKTRONIX TCPA300/400 current probe amplifier

TEKTRONIX TCPA300/400 current probe amplifier

Product positioning

Product portfolio:

Amplifier: TCPA300 (supports TCP312/305/303 probes), TCPA400 (only supports TCP404XL probes);

Probe: TCP312（30A/100MHz）、TCP305（50A/50MHz）、TCP303（150A/15MHz）、TCP404XL（750A/2MHz， Discontinuous).

Safe operation and system configuration

1. Core security standards

Prohibited live operation: Before connecting/disconnecting the probe/test line, the voltage source must be cut off to avoid insulation breakdown inside the probe;

Terminal matching requirements: The amplifier output needs to be connected to a 50 Ω load (oscilloscope or 50 Ω through terminal), otherwise the NOT TERMINATED IN 50 Ω LED will light up, affecting measurement accuracy;

Wire usage restrictions:

TCP312/305: Only insulated wires can be tested, and contact with exposed conductors is prohibited;

TCP303/404XL: can measure exposed conductors, but the probe needs to be removed and installed after power failure;

Environmental restrictions: Prohibit humid/explosive environments, working humidity of 5% -95% (≤ 30 ℃), 5% -85% (>30 ℃ -+50 ℃), non condensing.

2. System configuration and connection

(1) System composition

A complete current measurement system requires three parts:

TCPA300/400 amplifier: converts probe induced current into proportional voltage;

TCP300/400 series probe: clamp type induction current (effective after sliding cover locking);

Oscilloscope: requires a 50 Ω input impedance (if not available, add a 50 Ω straight through terminal), and the recommended bandwidth is 5 times the probe (e.g. TCP312 requires ≥ 500MHz oscilloscope).

(2) Connection steps

Amplifier → Oscilloscope:

TEKPROBE compatible oscilloscope: use TEKPROBE interface cable;

Non compatible oscilloscope: use 50 Ω BNC wire, set the oscilloscope input to 50 Ω;

Probe → Amplifier: Align the red marked points of the probe and amplifier, and lock them in place (do not twist);

Preheating: All equipment should be powered on and preheated for 20 minutes to ensure thermal stability.

Core Function Operation Guide

1. Key operations of the probe

(1) Demagnetization and automatic balancing (mandatory steps)

Function: Eliminate residual magnetism in the probe core, offset DC offset in the amplifier, and avoid measurement errors;

Trigger conditions: The probe slide is locked and disconnected from the live conductor;

Operation steps:

Press the PROBE DEGAUSS AUTOBALANCE button on the amplifier;

Wait for 5 seconds, the LED will flash from orange to green (successful), red (failed, terminal/probe connection needs to be checked);

Trigger scenarios: after startup, replacement of probe, overload, exposure to strong magnetic field.

(2) Sliding operation (different probe differences)

Probe model, sliding cover, opening method, locking method, precautions

TCP312/305 pulls the sliding cover backwards and pushes it forward until the buckle is fixed, only clamping the insulated wire

TCP303/404XL press lock+press handle release handle+press lock can clamp exposed wires (power-off operation)

2. Amplifier core control

(1) Key buttons and indicators

Control/indication function description exception handling

The COUPLING key switches between AC/DC coupling (AC only measures AC, DC measures AC/DC), and flashing indicates the display of Error Code

The RANGE key (TCPA300) switches the range (1/5/10/50A/V), and the LED indicates the current range. If the LED is not on, it means that the probe is not connected

PROBE OPEN LED probe slide not locked and turns off after locking the slide

OVERLOAD LED red: current beyond continuous range; Orange: Overtemperature; Flashing: Both exceed power-off cooling+demagnetization

NOT TERMINATED LED amplifier output not connected to 50 Ω load. Check oscilloscope impedance or add terminal

(2) Manual balancing (under DC coupling)

Function: Fine tune DC offset to improve measurement accuracy;

Operation: Press the MANUAL BALANCE key (left and right keys to adjust the offset direction), the LED lights up to indicate entering manual mode;

Limitation: Only DC coupling is effective, disabled under AC coupling.

3. Measurement process (taking DC current as an example)

Preheat the system for 20 minutes, set the amplifier to DC coupling, and set the oscilloscope input to 50 Ω;

Probe slide lock (no conductor), perform demagnetization/automatic balancing;

Adjust the grounding reference of the oscilloscope to the target scale;

Open the probe slide cover, clamp the tested conductor (probe arrow pointing in the normal current direction: positive → negative), and lock the slide cover;

Adjust the oscilloscope time base, trigger and gain, and read the current value (current=oscilloscope voltage value/amplifier range, for example, 2V corresponds to 10A at 5A/V range).

Performance validation and calibration

1. Preconditions for Performance Verification

Environmental conditions: temperature 23 ℃± 5 ℃, humidity meets requirements, no strong magnetic field;

Equipment requirements: current source (0.1% accuracy), DMM (5.5bit resolution), high-frequency current loop, etc. (see Table 5-3/5-11/5-17 for details);

Data recording: Corresponding test record forms (such as TCPA300 Table 5-16, TCP305 Table 5-29) need to be filled out.

2. Core testing items (amplifier+probe)

(1) DC gain accuracy test (taking TCP305 as an example)

Equipment connection: current source → 5-turn current loop → probe → amplifier → DMM (50 Ω terminal);

Test steps:

After demagnetization, the probe clamps the current loop and the current source outputs+1.00A;

Record the DMM voltage value M1, and then output -1.00A to record M2;

Calculation error:% Error=[(M1-M2) -2 × VE]/(2 × VE) × 100% (VE is the expected voltage, such as 1A corresponding to 1V in the 5A/V range);

Qualified range: ≤± 3% (guaranteed value), ≤± 1% (typical value).

(2) Bandwidth test (using TCP312 as an example)

Equipment connection: level sine wave generator → high-frequency current loop → probe → amplifier → oscilloscope;

Test steps:

The generator outputs a 3MHz, 3Vpp signal and records the oscilloscope peak to peak value M1;

Adjust the generator frequency to 100MHz (TCP312 bandwidth) and record M2;

Verification: (M2/M1) × 1.18 ≥ 0.707 (1.18 is the impedance correction factor);

Qualified range: -3dB bandwidth ≥ 100MHz.

(3) Rise time test (taking TCP404XL as an example)

Equipment connection: High voltage pulse generator → Built in current loop → Probe → Amplifier → Oscilloscope;

Test steps:

The generator outputs 5A, 250 μ s pulses, and the oscilloscope is set to 80ns/div;

Measure the rise time of pulses ranging from 10% to 90%;

Qualified range: ≤ 175ns (derived from a bandwidth of 2MHz: 0.35/2MHz=175ns).

3. Calibration adjustment (only operated by qualified personnel)

(1) Amplifier adjustment (TCPA300)

Prerequisite: The casing needs to be disassembled and a calibration adapter (174-4765-00) needs to be used;

Step: The current source outputs 0.100A, adjust the corresponding range potentiometer (such as adjusting the 25 Ω potentiometer for 5A/V) to make the DMM voltage meet the expected value (such as 0.1A corresponding to 0.25V at 5A/V range).

(2) Probe adjustment (TCP305/312)

DC gain adjustment: Open the probe housing and adjust the DC gain potentiometer to make the DMM voltage error ≤ ± 3% (refer to Table 6-7);

Attention: Record the original position before adjustment to avoid exceeding the specifications.

Troubleshooting and Maintenance

1. Common faults and solutions

Possible causes and solutions for the fault phenomenon

Demagnetization failed (LED red), 50 Ω load not connected, probe not locked, check terminal+lock slide cover

OVERLOAD LED constantly on, current exceeding range, probe overheating, current reduction+power-off cooling+demagnetization

The measurement value is not accurate without demagnetization, the range is selected incorrectly, the terminal is not connected to demagnetization+check the range+check the 50 Ω load

The probe without output signal is not connected, and the coupling is set to AC (measuring DC). Connect the probe and switch the DC coupling

2. Interpretation of Error Code

Display mode: AC/DC coupled LED flashes alternately, and 4 fault LEDs (PROBE OPEN is MSB, NONCOMPATIBLE is LSB) display a 4-digit binary code;

Common code:

Code 1: No Hall element detected in the probe → Reconnect or replace the probe;

Code 2: DC offset calibration failed → restart amplifier+demagnetization;

Code 15: Internal software error - If restarting is ineffective, contact after-sales service.

3. Daily maintenance

Cleaning: Wipe the outer shell with 75% isopropanol, and do not use solvents such as benzene/acetone;

Storage: Non working temperature -40 ℃ -+75 ℃, avoid moisture/dust;

Calibration cycle: It is recommended to calibrate once a year, with a reference frequency error (± 10ppm) valid for one year.

Accessories and Replacement Parts

1. Standard accessories (included with the product)

Category, accessory name, purpose

Amplifier accessory 50 Ω straight through terminal (011-0049-02) matching output impedance

Connect the TEKPROBE interface cable (012-1605-00) to the TEKPROBE oscilloscope

BNC line (012-0117-00) connected to non TEKPROBE oscilloscope

Probe accessories Probe cover (016-1923-00) protects the probe

Grounding lead (196-3120-01) probe grounding

2. Key replacement parts (partial)

Component type, model, and part number

TCPA300 motherboard circuit motherboard 671-5434-00

TCP305 coil current transformer component 120-184-00

TCP404XL cable probe cable assembly 174-4816-00

Amplifier fan axial fan (12VDC) 119-6721-00