BE1-87B — high-impedance bus differential protection relay
BE1-87B is a high-impedance differential relay for bus protection and other objects with a high-impedance differential scheme. It comes in a single-phase S1 case, three-phase M1 and 19-inch cases, with two time delay options, A1 and A2. It can replace PVD21B and PVD21D differential voltage relays in an existing case.
- Principle
- high-impedance differential protection
- Cases
- single-phase S1, three-phase M1, three-phase 19-inch rack
- Diagnostics
- CT circuit supervision, steady-state unbalance alarm
- Time delays
- A1: instantaneous / 20 ms; A2: instantaneous / 2 ms
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
BE1-87B is a high-impedance differential relay for fast protection of busbars and other objects with a high-impedance differential scheme in utility and industrial power systems. The high-impedance principle has been proven in practice and gives high speed and selectivity. During an external short circuit the voltage across the relay stays low, while during a fault inside the protected zone it rises sharply.
The relay includes diagnostics of the CT circuits and an alarm for steady-state imbalance. These help check the external wiring and prevent false operation. Time parameters are configured, the burden is low, so the load on the battery is small.
Compact and economical versions are available: a single-phase S1 case, a three-phase M1 case and a three-phase 19-inch case for rack mounting. Two time delay options are offered, and in each of them a jumper selects instantaneous operation or a deliberate delay. In variant A1 the instantaneous position gives maximum speed, while a 20 ms delay prevents operation during brief faults in a zone protected by a fast-acting fuse. In variant A2 a 2 ms delay prevents false trips during very short disturbances, for example close lightning strikes.
The relay and the system in the case are tested with test plugs. A diagnostic kit (part number 9282300014) is available for checking the CT circuits, and an extender card (part number 9112930101) for servicing the boards. In the high-impedance scheme the CTs of all feeders of the bus are connected in parallel, and a high-resistance relay is connected in the differential circuit. During external faults, even when one CT saturates, the voltage on the relay stays below the setpoint, so the protection does not operate. CT circuit diagnostics detect an open circuit or damaged secondary wiring, and the steady-state imbalance alarm shows a prolonged imbalance in the circuit. This simplifies commissioning and periodic testing.
BE1-87B is produced as a ready replacement for PVD21B and PVD21D differential voltage relays. It is installed in an existing PVD M1 case (part number 9282300111). For schemes with a large number of feeders, the manufacturer offers low-impedance busbar differential protection based on BE1-FLEX with monitoring of up to 28 CTs.
Technical specifications
| Principle | high-impedance differential protection |
|---|---|
| Cases | single-phase S1, three-phase M1, three-phase 19-inch rack |
| Diagnostics | CT circuit supervision, steady-state unbalance alarm |
| Time delays | A1: instantaneous / 20 ms; A2: instantaneous / 2 ms |
| Retrofit | replaces PVD21B/PVD21D in M1 case (part number 9282300111) |
Request a price and lead time
BE1-87B — high-impedance bus differential protection relay. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
Which cases are available for the BE1-87B?
A single-phase S1 case, a three-phase M1 case and a three-phase 19-inch case for rack mounting.
How do the A1 and A2 time delay options differ?
In option A1 a jumper selects instantaneous operation or a 20 ms delay. In option A2 it selects instantaneous operation or a 2 ms delay. The 20 ms delay suits a zone protected by a fast-acting fuse, and the 2 ms delay suits nearby lightning strikes.
Can the BE1-87B replace a PVD21B or PVD21D differential voltage relay?
Yes, the relay mounts in an existing PVD M1 case without modification, part number 9282300111.
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