Scope of this technical record
Braking-unit, resistor and thermal evidence path for SJ300 / L300P E07 cases during deceleration or repeated stopping.
Braking resistors can run hot and braking circuits remain hazardous. Do not bypass protection or test resistor circuits casually.
Hitachi braking unit / resistor path
The resistor route requires value, wiring, duty and heat evidence before a repair claim.
The brake route must be proven as a system
A resistor photo is not enough evidence. The route requires value, power, duty, thermal switch, wiring, BDU arrangement and evidence of how often the machine stops. A resistor that is healthy in isolation can still be wrong for the duty cycle.
For larger ratings, external braking-unit identity matters. For small ratings, built-in braking capability and optional resistor selection matter. The hardware route changes with frame size.
Field record checklist
- Built-in or external BDU
- Resistor value
- Resistor duty
- Thermal switch
- Wiring and heat marks
Technical basis and reference documents
This is an independent editorial technical reference. Original manufacturer documentation remains controlling for installation, repair and commissioning decisions.
Defines the status-at-trip context and links E07 to DC-bus overvoltage evidence.
Lists E06 braking resistor overload and E07 overvoltage protection caused by regenerative motor energy.
Shows that braking capability, resistor value, duty cycle and external braking units vary by rating.
Describes overvoltage detection by regenerated motor energy or high incoming AC voltage and highlights BRD-duty context.
Turn this record into a qualified service request
A repair decision is much more reliable when the request includes the exact identity of the drive, the first fault evidence and the machine condition when the symptom appeared.
- Complete drive type code / MLFB or nameplate model
- Fault code, fault value and first event before reset
- When the event appears: power-up, enable, ramp, run, decel or stop
- Motor/cable connected or isolated during the symptom
- Visible board, option-card, module and connector identifiers
- Previous repair history, replacement parts and repeat-failure pattern