What are the differences between spring-operated and permanent magnet brakes? How are they influenced by free-wheeling diode and spark suppressors?
• The Spring-Operated Brake normally opens at approx. 20 V and closes at approx. 3 V (values depend on size and spring type) • A Permanent Magnet Brake opens at approx. 20 V and closes at approx. 16 V => this may cause the brake to close in case of voltage fluctuations • Free-wheeling diodes and spark suppressors protect the switching contact in case of switching on the DC side (for 24V brakes) • If free-wheeling diodes are used, inductive voltage peaks are decreased. This is not the case with spark suppressors => 6 to 10 times of the brake closing time if a free-wheeling diode is used (compared to spark suppressors) • If permanent magnet brakes are used the immense time difference is not really perceptible (closes at 16 V) – unlike spring-operated brakes, as the voltage decrease to 3 V takes considerably longer. This means that the closing time of permanent magnet brake and spring-operated brake is different if free-wheeling diodes are used. Therefore, spark suppressors should be pref
