Capacitor Discharge Units
A capacitor discharge unit is a panel component in the form of a discharge coil that drains, within seconds, the voltage remaining on a power factor correction capacitor after it is disconnected. It is connected across the capacitor terminals in automatic power factor correction panels where steps switch in and out frequently, and is used to shorten the discharge time that must elapse before a step is re-energized. This category includes the Entes DU-3 discharge unit rated 200-480 V AC and the Siemens 4AJ9903-2YC discharge coil; in the Siemens product data, the discharge time is given as under 10 seconds, with one coil specified for banks up to 50 kVAr and two coils for banks between 50 and 100 kVAr. Choose the discharge unit by the rated voltage of the capacitor step, the step power (kVAr), the desired discharge time and the number of units required per step. A discharge unit should not be confused with the fixed discharge resistor on the capacitor: the resistor drains the capacitor over a longer time, whereas the unit is added so that the step can be re-energized at short intervals.
Products
- Entes DU-3 Capacitor Discharge Unit, 200-480VAC — Entes · SKU: M0880 · TRY 1,184.40 · Made to order
- Siemens 4RB9810-0AA00 Discharge Resistor EW22, 1 steps — Siemens · SKU: 4RB9810-0AA00 · TRY 7,199.00 · Made to order
- Siemens 4AJ9903-2YC Capacitor Accessory — Siemens · SKU: 4AJ9903-2YC · TRY 5,180.00 · In stock
How to choose Capacitor Discharge Units
A capacitor discharge unit is a panel component in the form of a discharge coil that drains, within seconds, the voltage remaining on a power factor correction capacitor after it is disconnected. It is connected across the capacitor terminals in automatic power factor correction panels where steps switch in and out frequently, and is used to shorten the discharge time that must elapse before a step is re-energized.
- Take reactive power demand and harmonic distortion levels from site measurements or project calculations.
- Compare kVAr step sizes, rated voltage and step count against the compensation panel layout.
- Select capacitor duty contactors, harmonic filter reactors and discharge resistors together with the capacitor bank.
Frequently asked questions
What is Capacitor Discharge Units and where is it used?
A capacitor discharge unit is a panel component in the form of a discharge coil that drains, within seconds, the voltage remaining on a power factor correction capacitor after it is disconnected. It is connected across the capacitor terminals in automatic power factor correction panels where steps switch in and out frequently, and is used to shorten the discharge time that must elapse before a step is re-energized.
What should I compare when choosing Capacitor Discharge Units?
Choose the discharge unit by the rated voltage of the capacitor step, the step power (kVAr), the desired discharge time and the number of units required per step.
Where can I find technical details for Capacitor Discharge Units products?
A discharge unit should not be confused with the fixed discharge resistor on the capacitor: the resistor drains the capacitor over a longer time, whereas the unit is added so that the step can be re-energized at short intervals.