Phase demodulators are used to connect DC units to alternating voltage supplies. Due to automatic switching from the applied overexcitation voltage to the holding voltage, it is possible to energise brakes with a holding voltage for shorter switching times with overexcitation and to reduce power dissipation after the armature disk has attracted.
The phase demodulator is used for an input voltage of 230 or 400 VAC. The coil is energised after the input voltage is switched on using overexcitation voltage. After the overexcitation time, the unit switches automatically to the holding voltage. Apart from this, the phase demodulator has an integrated automatic DC-side disconnection. In contrast to the usual DC-side disconnection, no further protective measures or external components are required. The DC-side disconnection is activated as a standard measure (terminals 3 and 4 are not wired) and causes short switching times on the electromagnetic consumer. The integrated automatic DC-side disconnection can be deactivated by fitting a bridge between the terminals 3 and 4. The coil is de-energised via an internal freewheeling diode. This has the advantages of soft brakings and quieter switching noises. However, this substantially lengthens the switching times (approx. 6 – 10 times).