Siemens SDR 15.5 kV Instruction Manual page 9

Current transformers (CTs)
The type SDR vacuum recloser is equipped
with one integrated current transformer per
pole. The current transformer is the
conventional type (iron core magnetic) and
has a ratio of 800 A:1 A. It is for protection
purposes and optimized for operation with
the controller (see controller on page 11).
The secondary signal is based on IEC 60044-1
and the IEC accuracy is 0.5 VA 5P20.
The secondary wires of the CT are connected
to a varistor for each pole in the switch unit.
This prevents the occurrence of high voltages
(due to open-circuit CT secondary) if the
control cable is removed while the switch unit
is in operation. Do not disable the varistor
circuit. The signal transfer from the CTs to the
controller is by the control cable. A separate
cable is not required.
Voltage sensor (optional)
The SDR vacuum recloser can be equipped
with integrated resistive voltage sensors
(optional). The integrated resistive voltage
sensors have a high level of accuracy and are
used both for measurement and protection
purposes. The ratio is adapted to operation
with the controller (see controller on page
11) and provides a 110 V/√3 secondary signal
with rated primary voltage applied to the
recloser.
The voltage sensor and CT outputs are
coordinated with Siemens controllers. If a
non-Siemens controller is used, it is the
controller vendor's obligation to properly
coordinate their controller with the voltage
sensors and CTs provided in the type SDR
distribution vacuum recloser.
An optional separate sensor cable equipped
with special screening (shield) is used for the
signal transfer from the voltage sensors to the
controller. This results in a high level of
accuracy and protection against disturbances.
The sensor cable is connected at the back of
the operating mechanism housing next to the
control cable.
The secondary wires of the voltage sensors
are connected to a varistor for each pole in
the switch unit. This prevents the occurrence
of high voltage on the sensor cable if the
sensor cable is removed while the switch unit
is in operation. Do not disable the varistor
circuit.
Operating mechanism
The operating mechanism for the vacuum
interrupters is located in a metal housing. To
meet the required fast reclosing cycles, a
magnetic actuator with capacitors as energy
storage drives the switch unit. A gang-
operated mechanism connects the magnetic
actuator with the vacuum interrupters.
The operating mechanism is equipped with
anti-condensation space heaters. It is
operated together with the heating in the
controller and controlled by a thermostat.
A mechanical position indicator is easily
visible from the ground and shows the
current switch position of the recloser (open
= green, closed = red). The colored display is
reflective in the dark when using a flashlight.
Lockout handle
A lockout handle with ring protrudes from the
operating mechanism housing. The ring is
colored bright yellow and is therefore easily
seen.
By pulling the lockout handle, the recloser
opens and remains locked in this position.
The locking has a dual electrical effect; it
locks out both the controller and the
electronics. It also mechanically locks the
magnetic actuator.
As long as the lockout handle is pulled out, it
is not possible to close the switch unit
electrically, whether locally or from a remote
location. The interlocking is not reset until the
lockout handle has been completely pushed
in. After this, the switch unit can be closed
electrically, either locally or remotely.
The switching is described in the Operation
section of this instruction manual (see page
22).
Note: The lockout handle must be fully
pushed in or the interlocking will prevent
closing of the recloser.
Color of
Recloser
position
position
indicator
Closed Red
Open Green
Table 1: Recloser position and
indicator color
3
1 2
1. Lockout handle
2. Position indicator
3. Operations counter
Figure 6: Operating mechanism
(viewed from below)
1 2
1. Lockout handle
2. Position indicator
Figure 7: Operating mechanism
with lockout handle pulled out
(viewed from below)
9