Is there a facility to remotely trip a RCCB/RCD? I'd like to put an emergency power off button on my server room and am wondering if I really need an RCCB/RCD /and/ a contactor?
You need an extra option for this
Assuming your EPO switch is a normally open type, the typical way to do this at the panel uses a breaker with a shunt trip or shunt release option fitted, which will trip the breaker when power is applied to the shunt trip's terminals. Most North American panelboard-type MCBs can be ordered with a shunt trip as a factory option -- however, it's limited in nature, and often cannot be applied to specialty breakers such as GFCIs/AFCIs.
However, what you can do is provide GFCI, GFPE, or AFCI protection for the branch circuits, and put the shunt trip on the main or feeder shutoff breaker. That way, you only need one custom-ordered breaker instead of several, and also circumvent the incompatibility between specialty breakers and shunt trip accessories.
If you were back home...
If you were on the European system, however, DIN rail breakers are rather modular (compared to North American loadcenter/panelboard-type MCBs), so shunt trips for RCCBs are available as a general rule. Most can be either factory or field fitted depending on the situation and breaker make/model.
(If you had a normally closed EPO, you'd need an undervoltage release option instead -- it's the inverse function of a shunt trip. These are not as common as shunt trips, especially in North America although some European breaker lines have restrictions on the employment of their undervoltage release options that aren't present on their shunt trips.)
You could use a RCD tester. This is a device which places a sensibly sized load between hot and ground, aiming to induce more fault current than the RCD's trip threshold, proving the RCD works.
You could make one yourself out of a big red pushbutton switch and a right sized resistor. Take the RCD's current rating (e.g. 30ma), multiply by 5 to get a nice sure trip, that is I (current). You know your mains voltage, that is E (voltage). Apply Ohm's Law
E=IR, solve for R and your resistor value pops out. Size (wattage) of resistor: apply Watt's Law
For the original poster and subsequent readers, I want to first clarify the terms used and summarise the purpose of each item, which should then help answer the question.
- RCD = Residual Current Device
- RCCB = Residual Current Circuit Breaker
- RCBO = Residual Current Circuit Breaker with Overcurrent/Overload Protection
RCD and RCCB are two names for the same item. These terms are typically used in the UK to refer to a current-operated fault detector. If Line/Phase voltage does not equal Neutral voltage under load, current is leaking to earth/ground, possibly through someone's body. By breaking the circuit within defined tolerances of current and time, potential electric shock is avoided. An RCBO combines the function of an overcurrent device like a thermo-magnetic miniature circuit breaker or a fuse, with that of an RCD.
In North American terminology, the RCD is equivalent to a GFCI = Ground Fault Circuit Interruptor. GFPE = Ground Fault Protection Equipment has higher tolerances and a different purpose: the detection of earth/ground leakage that could damage an appliance but that is insufficient to operate an overcurrent device (e.g. a fuse). The equivalent to an RCBO is a GFCI 'breaker'.
In terms of remotely testing an RCD and thus intentionally causing it to operate (trip), one product I found from an Australian company is the Rapid Test RTTUWF RCD Test Module with Wi-Fi communications, so such devices do exist. This will be safer than a DIY solution to deliberately create imbalance between phase and neutral.
Of course, you'll need extant power to operate any such test device and the network used to trigger it, so it would need to be isolated from the RCD and/or connected to a UPS. It's unclear whether something similar exists for the 110V/60Hz system in Colombia, but the US market may have something designed for this purpose at these voltages.
Remember, the RCD test function is intended to test the device, not to reliably operate it. Its purpose is to verify whether the RCD will operate, which in some cases, it may not. Therefore testing is not a reliable way to de-energize the circuit.
This is the function of an Emergency Power Off (EPO) switch, so that should clearly answer your question of whether you need both - yes, you do. Depending on your purpose for the EPO, you may need a switch or similar device at the power to the UPS and/or from it. APC does offer remote EPO systems for data centers, but this may be overkill.