Weltronic H70-T02A S430-V1.2 Weld Timer PLC

The Weltronic H70-T02A is a programmable inverter weld timer used in resistance welding systems. It operates with software version S430-V1.2 (and includes S412-V1.1 control board). The unit provides precise timing and current control for spot, projection, and seam welding processes. It is designed to interface with weld heads, transformers, and external PLCs for automated welding cells.

Control Features

The H70-T02A generates firing pulses for inverter-based weld power supplies (typically medium frequency DC). Key parameters include:

• Weld time: adjustable 0–999 cycles (1 cycle = 20ms at 50Hz).

• Squeeze time, hold time, and off time: 0–999 cycles independently.

• Current control: constant current or constant voltage modes, with feedback from a toroidal coil (welding transformer).

• Slope-up and slope-down: 0–99 cycles for gradual current increase/decrease.

The unit features 32 programmable weld schedules, each storing all parameters.

Hardware Specifications

The controller includes a S412-V1.1 main board and a 100C03-400-0 I/O interface board. Inputs: 8 opto-isolated 24V DC (start, stop, schedule select). Outputs: 8 relay outputs (2A at 250V AC) for weld enable, ready, and fault signals. An analog output (0–10V) provides real-time weld current monitoring. The unit has an RS-232 port for PC communication (parameter upload/download).

Inverter Control Output

The module generates 0–10V analog control signal (or 4–20mA) for the welding inverter. It also provides IGBT gate drive signals (15V, 5 kHz to 20 kHz) via a 15-pin D-sub connector. The unit monitors inverter DC bus voltage and temperature, and shuts down on faults (overcurrent, overtemp, shorted SCR).

User Interface and Programming

A built-in 4-line x 20 character LCD display shows parameters and diagnostics. Membrane keypad allows direct programming. The controller stores up to 100 weld logs (date, time, current, and OK/NOK). The unit supports a remote pendant (Weltronic H70-P) for operator control.

Power and Environment

Supply voltage: 115/230V AC (switchable, 50-60Hz). Power consumption: 30 VA. Dimensions: 210 mm width x 170 mm height x 100 mm depth. Weight: 2.5 kg. Operating temperature: 0 to 50°C. Storage: -20 to 70°C. Protection class: IP20 (for panel mounting). The unit uses a 3AG 1A fuse on the AC input.

Communication and PLC Integration

The H70-T02A can communicate with a main PLC via discrete I/O (handshaking) or serial RS-485 (Modbus RTU). Typical handshake signals: Start Request (from PLC), Weld Complete (to PLC), and OK/NOK (pass/fail). The unit can also receive weld schedule numbers from the PLC.

Diagnostics and Fault Codes

Self-diagnostic codes include: E01 (primary SCR short), E02 (current feedback lost), E03 (inverter overtemp), E04 (no weld fire). Fault history is retained in non-volatile memory. An external alarm output can be connected to a tower light.

Typical Applications

Used in automotive body welding lines, battery tab welding, and appliance manufacturing. The inverter weld timer is suitable for aluminum and high-strength steel spot welding requiring precise heat control.

Ordering and Documentation

Model: H70-T02A (S430-V1.2 firmware). Includes S412-V1.1 board and I/O board 100C03-400-0. Manual: Weltronic H70 Series User Guide (Pub. 700-029).