Protection Relay Settings Quick Reference Card
Free download · 85 × 54mm (credit card size)
This pocket reference card puts essential protection relay settings data at your fingertips. The front covers the IDMT tripping formula t = TMS × k / (I/Is)^α − 1 with constants for Standard Inverse (α=0.02, k=0.14), Very Inverse (α=1.0, k=13.5), and Extremely Inverse (α=2.0, k=80.0) curves. Includes definite time element guide and typical pickup settings: 1.0–1.2× rated current for overload, 5–10× for instantaneous. The reverse covers Coordination Time Interval (CTI) rules (0.2–0.4s), relay hierarchy from utility through to motor protection, and highset vs lowset element overview. QR code links to ECalPro Protection Coordination Calculator.
What's Included
How to Print
- ●Recommended paper: 250–300gsm cardstock
- ●Print double-sided, flip on short edge
- ●Cut along crop marks with a paper trimmer
- ●Laminate with 80–125 micron pouches for durability
- ●Fits in wallet, toolbox, or pocket
Try the Interactive Calculator
Need precise calculations beyond quick reference? Try our free online calculator with full clause references and professional report output.
Open CalculatorRelated Downloads
CB Selection
Free printable LV circuit breaker selection guide card. MCCB ratings explained (In, Ics, Icu, Icw), selectivity types, Type 1 vs Type 2 coordination, cascading rules.
Protection Coord Poster
Free printable A3 protection coordination poster. Time-current characteristic curves for typical system hierarchy. CTI zones, instantaneous pickup bands, coordination rules.
Frequently Asked Questions
What paper should I print this on?
Print on 250–300gsm cardstock for durability. Use duplex (double-sided) printing and cut along the crop marks. Laminate with 80–125 micron pouches for long-term site use.
Can I distribute this to my team?
Yes. All ECalPro reference cards are free to download, print, and distribute within your organization. Keep the ECalPro branding and QR code intact.
What standard does this reference?
This card references IEC 60255-151 (IDMT overcurrent relays) and IEC 60255-181 (functional requirements for frequency protection). Curve constants are per IEC 60255-151 Table 1.
How often is this updated?
Updated when relay standards are revised. Current card reflects the latest IEC 60255 series.