BASLER ELECTRIC BE1-851 OVERCURRENT PROTECTION RELAY MECHANISM
BASLER ELECTRIC BE1-851 OVERCURRENT PROTECTION RELAY MECHANISM
The BE1-951 Overcurrent Protection System provides complete circuit protection with multiple
overcurrent elements and is intended for use in any directional or non-directional overcurrent application.
Its unique capabilities make it ideally suited for applications where:
• Applications that require low burden to extend the linear range of CTs.
• Applications that require high accuracy across a wide frequency range such as for motor,
generator, and generator step-up transformer protection, or in co-generation facilities.
• Applications that require the flexibility provided by wide settings range, multiple setting groups,
and multiple coordination curves in one unit.
• Applications that require the economy and space savings provided by a multifunction, multiphase
unit. This one unit can provide all of the protection, control, metering, and local and remote
indication functions required on a typical circuit.
• Applications that require directional control and fault locating.
• Applications requiring protection of an intertie between dispersed storage and generation facilities
(DSG) and a utility.
• Transformer backup applications where overexcitation protection is required.
• Applications that require communications and protocol support.
• Applications where the capabilities of a digital multifunction relay are required, yet draw out
construction is also desirable.
• Applications where bus protection is provided by a high-speed overcurrent blocking scheme on
the transformer bus mains instead of a dedicated bus differential circuit.
• Applications where the small size and limited behind-panel projection facilitates modernizing
protection and control systems in existing substations.
• Applications using Ethernet communication, programmable email notifications, and live metering
information via an embedded web server (with BESTnet option).
• Applications requiring Modbus/TCP Ethernet communications (with Modbus/TCP option).
Model and Style Number Description
General
The BE1-951 Relay electrical characteristics and operational features are defined by a combination of
letters and numbers that make up the style number. The model number, together with the style number,
describe the options included in a specific device and appear in the clear window on the front panel and
on a sticker located inside the case. Upon receipt of a relay, be sure to check the style number against
the requisition and the packing list to ensure that they agree.
Sample Style Number
BE1-851
Style number identification chart, Figure 1-1. defines the electrical characteristics and operational features
included in BE1-951 Relays. For example, if the style number were E3N1R0Y, the device would have the
following characteristics and features:
BE1-951 —
(E) – 5 ampere nominal system with 5 ampere independent ground input
(3) – Three-phase voltage sensing
(N) – Not applicable
(1) – 48/125 Vac/Vdc power supply
(R) – Single ended case, normally open alarm output
(0) – ASCII over RS-485. No Ethernet
(Y) – 4000 point Data Array
Figure 1-1. Style Chart
Operational Specifications
BE1-951 relays used in a 50/60 Hz system have the following features and capabilities. For 25 Hz
operational specifications, refer to Appendix D, 25 Hz Operational Specifications.
Metered Current Values and Accuracy
5 Aac Nominal Range …………………………………………….. 0.5 to 15 Aac
1 Aac Nominal Range …………………………………………….. 0.1 to 3.0 Aac
Accuracy ………………………………………………………………. ±1% of reading, ±1 least significant digit at 25°C
Temperature Dependence ………………………………………. ≤ ±0.02% per °C
Metered Voltage Values and Accuracy
3-wire Range ………………………………………………………… 0 to 300 VL-L
4-wire Range ………………………………………………………… 0 to 300 VL-L
Accuracy (10 to 75 hertz)
50 V to 300 V ………………………………………………………… ±0.5% of reading, ±1 least significant digit at 25°C
Temperature Dependence ………………………………………. ≤ ±0.02% per °C