Hilkar RC Type Output Filter Modules protect motors from high-voltage spikes generated by PWM motor drives using IGBT switching devices. With IGBT rise times typically between 50 ns and 200 ns, even short motor cables can produce voltage doubling at the motor terminals due to the travelling wave phenomenon.
Installed at the motor stator terminals, RC Type Output Filters suppress these transient overvoltages, reduce dv/dt stress, protect motor winding insulation, and improve the reliability and service life of the motor-drive system.
In PWM-driven motor systems, IGBT switching produces voltage pulses with rise times of only 50–200 ns. As these fast-rising pulses travel through the motor cable, an impedance mismatch at the motor terminals creates reflected waves that can significantly increase the peak voltage across the motor windings.
The magnitude of this voltage overshoot depends on factors such as cable length, IGBT switching speed, and the impedance characteristics of the motor. Under certain conditions, even cable lengths of 15–30 m can generate damaging overvoltages.
Hilkar RC Type Output Filter Modules are RC snubber networks installed directly at the motor terminals. They absorb the reflected wave energy, limit voltage overshoot to safe levels, reduce dv/dt stress, and protect the motor insulation system, thereby extending motor service life and preventing premature winding failures.
| HMT480 | HMT600 | HMT690 | |
|---|---|---|---|
| Module Voltage (V) | 340–480 | 500–600 | 690 |
| Module Power (W) | 600 | 600 | 600 |
| Motor Power (kW) | 0.3–630 | 0.3–630 | 0.3–630 |
| PWM Frequency (kHz) | 2–8 | 2–8 | 2–5 |
| Maximum Cable Length (m) | 500 | 400 | 200 |
| Protection Degree | IP 20 | IP 20 | IP 20 |
For small motors, the driver's rated power must exceed the motor power by at least the module power.
- Reduces voltage spikes at motor terminals
- Installs directly at motor stator terminals
- Supports motor ratings from 0.3 kW to 630 kW
- Available for 480 V, 600 V and 690 V systems
- IP 20 enclosure for panel or junction box mounting
- Compatible with all major PWM drive brands
- Low power dissipation (600 W per module)
- Extends motor insulation life by suppressing voltage reflections
Hilkar designs each Motor Termination Unit to match the specific motor drive, cable, and motor combination. The RC network is optimized according to system voltage, cable length, PWM switching frequency, and motor rating to ensure maximum protection and performance.
Custom solutions are available for non-standard voltages, higher IP protection degrees, forced cooling, and special enclosure configurations to meet specific application requirements.
All Motor Termination Units are factory tested to ensure reliable performance and long-term operation.
- Insulation resistance measurement
- Capacitance and resistance verification
- High voltage withstand test
- Visual and dimensional inspection
- Thermal performance verification under rated operating conditions