SZR APC automatic transfer switch cabinet for LV with diesel generator start
Country: Poland · Model: SZR APC
The SZR APC low-voltage automatic transfer switch cabinet moves loads from the main supply to a standby network or a diesel generator set, starts the unit by itself and returns the supply to the main feed once voltage is restored. It is installed in hospitals, high-rise and public buildings, data centres and industrial sites, where critical LV loads cannot be left without voltage.
- Functions
- automatic switching between main and standby supply or generator set; starting and stopping the unit; return to the main supply
- Time delays
- adjustable delays for voltage loss and voltage recovery
- Interlocking
- double electrical and software interlocks, optionally mechanical, against parallel operation
- Modes
- automatic and local manual
Technical specifications
| Functions | automatic switching between main and standby supply or generator set; starting and stopping the unit; return to the main supply |
|---|---|
| Time delays | adjustable delays for voltage loss and voltage recovery |
| Interlocking | double electrical and software interlocks, optionally mechanical, against parallel operation |
| Modes | automatic and local manual |
| Manufacturer | a company of a Polish electrical engineering group, Ostaszewo (Poland) |
Specifications are taken from the manufacturer’s technical documentation. Updated .
Description
The manufacturer derives the need for such automation from building regulations. A building where loss of voltage threatens the life or health of people or creates serious danger or large material losses is supplied from at least two independent sources with emergency lighting that switches on automatically, and in high-rise buildings one of the sources must be a generator. The cabinet reacts to an excessive drop or loss of voltage on the backed-up busbars from any cause and connects the standby supply only after checking that voltage of the required value is present on it. First it makes sure that the main supply breaker is open, so the standby supply is not switched onto a short circuit and unsynchronized sources do not run in parallel. The same task is backed up by double electrical and software interlocks of the actuating devices, and by mechanical ones if needed. The delays for voltage loss and recovery are coordinated with the transfer switches of upstream switchgear and with protection settings, to avoid unnecessary operations. After the mains returns, the unit stops once the set run-down time has passed. Operation is signalled, the cabinet is easy to take out of service, and the devices can be operated manually on site.
How to choose
The SZR APC versions differ in connection diagrams and in the technical data from the series catalogue, so selection starts with the type of standby supply (a second network or a generator set) and the current of the incoming feeds. For a generator set the voltage-loss delay is made longer than the operating time of the upper-level transfer switch, otherwise the generator will start needlessly. If manual switching between two feeds is enough, the RA I-0-II changeover switch for 160–1 250 A is used, and the outgoing lines are protected with RBK pro fuse switch disconnectors for 125–630 A.
Request a price and lead time
SZR APC automatic transfer switch cabinet for LV with diesel generator start. We reply within one business day.
Or email office@usk.ua or call +38 (044) 339-50-20.
FAQ
How does the SZR APC transfer switch cabinet start a diesel generator?
After the delay for loss of voltage on the main supply, the cabinet sends a start command to the unit, checks its voltage and only then connects the standby supply.
How does the SZR APC prevent the mains and the generator from running in parallel?
The actuating devices have double electrical and software interlocks, and mechanical ones if needed. Before connecting the standby supply, the cabinet also checks that the main supply breaker is open.
Can the SZR APC delays be coordinated with protections and upper-level transfer switches?
Yes, the delays for voltage loss and recovery are adjustable, so that the cabinet does not act ahead of the transfer switches of upstream switchgear.
Does the SZR APC cabinet have a manual control mode?
Yes, besides the automatic mode there is local manual control of the devices, which is convenient during maintenance.
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