Kendrion 7760016A00-0004, Руководство пользователя

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Operating Instructions BA 77 600..A00 // Last updated: 13/03/2020 // Page 11 of 33
3.3.1 DC power supply
The figure to the right shows the voltage curve after the field coil
(1.2) has been de-energised.
Attention!
The peak voltage U
Vmax
during disconnection without protective
circuit may reach several thousand V in the millisecond region.
This may cause irreversible damage to the field coil (1.2),
switching contacts and electronic components. Sparking will occur
on the switch during disconnection. Consequently, a protective
circuit must be provided to reduce the current during disconnection
and to limit the voltage. The maximum permitted overvoltage
during disconnection is 1500 V. If Kendrion rectifiers are used (see
Table 10/1), the protective circuit required for the built-in electronic
components and field coil (1.2) is included in the rectifier. This
does not apply to the external contacts required for DC side
switching as there would be no galvanic isolation of the external
contact.
Attention!
Sensitive electronic components (e.g. logical components) may also be damaged by the lower voltage.
3.3.2 AC power supply
Direct connection of the spring-applied single-disc brake to an AC power source is only possible if a rectifier is
used. The coupling times vary depending on the switching type (DC side switching or AC side switching).
Half-wave rectification:
In case of half-wave rectification, the U
2
coil voltage is lower by factor 0.445 than the rectifier input voltage.
Half-wave rectifiers produce voltage with high residual ripple which, depending on the brake size, may slightly
reduce the switching times when compared to bridge rectifiers. Due to the shorter switching times and the
lower coil voltage, half-wave rectifiers are generally preferred to bridge rectifiers. However, brake humming
may occur when small size brakes are used.
U
B
operating voltage (coil voltage)
U
Vmax
disconnection voltage
t
t
M
U
0,9 x M
2
B
U
U
Vmax
t
t
11
1
1
M
Fig. 11/1: Rectifier contact assignment for brakes with built-in rectifier (25.2)
Normal coupling time t
1
:
Shorter coupling time t
1
:
brake coil
In case of DC side switching, AC
side switching is also required.