Westinghouse Switch warranty Voltage Sensing Relays

Instruction Leaflet 30-470 (E)

Page 7

Table 1 — Interrupting, Closing and Withstand Rating —					Automatic Control
Robonic Type A
Robonic		rms symmetrical amperes			Voltage Sensing Relays
Continuous
					Ratings — 1.0 volt-ampere power consumption
Rating	600 Vac		480 Vac	120,208,240 Vac
					Input Coil Voltage — 120 volts at 50/60 hertz
30 to 100 amps	14,000		14,000	18,000
					Contact Rating — 3.0 amperes resistive at 120 volts
150 to 1000 amps	22,000		30,000	42,000	Duty — continuous
1200 to 3000 amps	100,000		100,000	125,000	Operating Temperature Ratings — -10°C to +55°C

Since type A Robonics employ magnetic only breakers, their interrupting, closing, and withstand ratings are the same value. Under fault conditions, with it’s “normal” breaker closed, a Robonic is required to withstand the energy let through of the normal service protective device while the fault is being cleared. At the same time, should the normal voltage fall below the voltage sensing relay’s selected value, – and if the alternate source were available, the Robonic could transfer before the normal service protective device cleared the fault.

This would require that the Robonic be capable of interrupting the protective device’s let through current. In addition, the Robonic could be required to close in on a fault. Thus can be seen the need for Robonics to have, interrupting, closing and withstand ratings.

The interrupting, closing and withstand ratings shown in Table 1 are those for standard type A Robonics. For higher values, consideration can be given to use of Robonics built with Mark 75, Tri-Pac or SCB breakers.

Table 2 — Maximum Upstream Circuit Protective Devices for

Type A Robonics, All Classes of Loads

Standard Robonic	Maximum Upstream	Maximum Upstream Fuse Rating		Description
Continuous	Breaker Frame Size			The device VS is an octual plug-in unit complete with solid-state
Rating (amperes)		Class J or L	Class K5 or R
30, 70, 100	EHB, FB, FB-P	100	100	sensing and a DPDT relay enclosed in a dust-tight, yellow capsule.
				The receptacles and plugs are designed to ensure a tight fit to reduce
150, 225	CA, JA, KA	225	225
				the possibility of coming loose through vibrations.
400	DA, LB, LA-P	400	400
600	LA600	600	600	The solid state sensing of the fixed model has been factory set for
800	MA, MC, NB-P	800	800
1000, 1200	NB, NC	1200	....	pickup and dropout values of 104 volts Ac and 84 volts Ac respectively.
1400, 2000	PB, PB-P, PCC	2000	....	The adjustable model voltage sensor has a variable range of pickup,
				92 volts to 140 volts Ac and dropout, 90 volts to 138 volts Ac with a
				close differential of 2 volts.

Table 3 — Maximum Upstream Circuit Protective Device for Type A Robonics, 90% or Larger Motor Load

Standard Robonic	Maximum Upstream	Maximum Upstream Fuse Rating
Continuous	Breaker Frame Size
Rating (amperes)		Class J or L	Class K5 or R
30, 70, 100	EHB,FB,HFB,FB-P	300	100
	LA-P,c/w 400 LAP10
150, 225	CA,JA,KA,HKA,LA	400	225
	HLA,LB,HLB,MA,NB
	LA-P,NB-P c/w 1000
	NB14 MC,NC
400	LA,HCA,LA-P,LB,MA	600	400
	HMA,NB,HNB,NB-P
	MC,HMC,NC,HNC
600	MA,HMA,MC,HMC	1200	600
	NB,NC,HNC,NB-P
800	MA,HMA,NB,HNB,	1200	....
	NB-P
	MC,HMC,NC,HNC
1000	NB,HNB,NC,HNC,PB-P	1200	....
1200	NB,HNB,NC,HNC,PB-P	1200	....
1400, 2000	PB,PB-P,PC	2000	....

The contacts being two pole double throw allows one set to be incorporated in the control scheme and an additional set for external connections if required.

Application

When used on the Robonic Automatic Transfer Switch as an under- voltage sensing device, they have been designated as devices VS. The standard Robonic Transfer Switch comes with one fixed voltage sensor, VS1, for single phase application and three fixed voltage sensors, VS1, VS2 and VS3, for three phase applications, all of which monitor the normal power source only.

The single phase voltage sensor is connected to the normal control transformer, NT, to monitor the normal source.

The three phase voltage sensors are connected to three smaller transformers, VST, which are connected in a delta-Wye configuration for use on all voltages, including 120/208 volts, none of which use the system neutral.