Chapter 4 – ‘1+N’ System Liebert Hipulse E Installation Manual
Single or '1+N' UPS System
Page 4-10 (07/04)
4.4.2 Castell Interlock
The Castell Interlock enables the operator to close/open the external maintenance bypass switch following the
procedure required to release/insert the key. The UPS Liebert Hipulse E system offers two types of Castell Interlock
options: mechanical and electromechanical. The type must be selected depending on the configuration of the system
installed in the plant.
Castell Interlock
Configuration of the UPS system Type of Castell Interlock
Two UPS's with parallel redundant connection (1+1) Mechanical Castell Interlock
Two UPS's with parallel power or
above two UPS's (1+N)
Electromechanical Castell Interlock
The Castell Interlock option is normally used in combination with the power isolators placed inside the external
maintenance bypass cabinet.
Note: The Liebert Hipulse E UPS system is already pre-arranged for the installation of this option.
This option comprises:
• A Castell Interlock with key (BP1) for each UPS of the system. The key is normally blocked and released only
when the UPS inverter turns off and the load is switched to the static bypass, depending on the active UPS
modules.
• A Castell key exchange box. This will receive the keys from all the UPS modules, then release another key
(BP2) to use in the Maintenance Bypass isolator.
• A Castell Interlock with key (BP2), situated on the external maintenance bypass isolator. As this isolator is
normally open and has no key, it can be closed only with the key (BP2) released by the Castell key exchange
box. The key is released only when the isolator is open.
• A Castell Interlock with key (BP2), situated on the UPS output isolator within the external maintenance bypass
cabinet. This isolator is normally closed and has a key. The key is released only when the isolator is open.
4.4.2.1 Electromechanical Castell Interlock
This option consists of a Castell key exchange box and of several Castell units with individual key. Their number varies
according to the number of UPS's present in the system.
The release of a specific key (BP1) occurs only when the inverter turns off. As a consequence thereof, the load is
transferred to the internal static bypass line (the switching operation occurs when the number of active UPS's is lower
that the number set in the menu of the operator control panel). The key, which is fixed in position by means of an
electromechanical device, can only be removed by pressing the energising button of the solenoid and when the green
indicator is on. The keys extracted from the UPS's (n BP1) enable to free a second key (BP2) from the Castell key
exchange box and to close the external maintenance bypass isolator, enabling the line that directly connects the bypass
mains to the load. To isolate the UPS system, it is necessary to open the UPS output isolator of the external bypass
cabinet, the protective devices at the input distribution panel and the battery circuit breaker. At this point, the load is
supplied by the direct line inside the maintenance bypass cabinet and it is possible to perform maintenance operations
or reparations on the UPS as it is completely isolated.
4.4.2.2 Mechanical Castell Interlock
The description above is valid also for this type of Castell unit, with the following exceptions:
• The maintenance bypass switch (Q3) of the UPS is closed before the external bypass isolator.
• The key (BP1) acts on the maintenance bypass isolator (Q3) blocking (or disengaging) a mechanical stop.
• No button needs to be pressed to extract the key (BP1) on the UPS.
The keys symbols of the Castell Interlocks can be customized to suit the needs of the customer.
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